Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study

Lawrence O'Leary; William B Sherwood; Michael G Fadel; Musa Barkeji

doi:10.3310/nihropenres.13543.2

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Research Article

Revised

Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study

[version 2; peer review: 2 approved]

Lawrence O'Leary^1,2, William B Sherwood¹, Michael G Fadel ^3,4, Musa Barkeji¹

PUBLISHED 23 Oct 2024

Author details Author details

¹ Department of General Surgery, West Middlesex University Hospital, London, TW7 6AF, UK
² Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 3GE, UK
³ Department of Surgery and Cancer, Imperial College London, London, W12 0NN, UK
⁴ Department of General Surgery, Chelsea and Westminster Hospital, London, SW10 9NH, UK

Lawrence O'Leary
Roles: Conceptualization, Data Curation, Formal Analysis, Investigation, Methodology, Resources, Software, Writing – Original Draft Preparation, Writing – Review & Editing

William B Sherwood
Roles: Conceptualization, Data Curation, Formal Analysis, Investigation, Methodology, Resources, Writing – Review & Editing

Michael G Fadel
Roles: Conceptualization, Data Curation, Formal Analysis, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Supervision, Validation, Writing – Review & Editing

Musa Barkeji
Roles: Conceptualization, Project Administration, Supervision, Visualization, Writing – Review & Editing

OPEN PEER REVIEW

REVIEWER STATUS

Abstract

Background

Routine group and save (G&S) testing is frequently performed prior to cholecystectomy, despite growing evidence that a targeted approach is safe and avoids unnecessary investigations. This retrospective cohort study explored frequency of testing in our unit, rates of peri-operative blood transfusion and pre-operative risk factors for requiring transfusion.

Methods

Health records of 453 consecutive adults who underwent cholecystectomy in a UK NHS trust were reviewed for blood transfusion up to 30 days post-operatively. We compared the need for transfusion against patient demographics, indication and urgency of surgery, and the number of prior emergency hospital attendances with gallstone complications. Logistic regression determined whether prior attendances with complications of gallstones independently predicted the need for transfusion.

Results

Peri-operative blood transfusions within 30 days of operation occurred in 1.1% of cases, with no requirement for uncrossmatched blood. Patients who received a blood transfusion tended to have higher American Society of Anesthesiologists (ASA) grades (p = 0.017), were more likely to have an underlying primary haematological malignancy (20.0% vs. 0.2%; p = 0.022) and prior emergency hospital attendances with gallstone complications (median 4 vs. 1; p < 0.001). Logistic regression showed each prior emergency attendance was associated with 4.6-fold odds of transfusion (p = 0.019). Receiver operating characteristic curve analysis showed an area under the curve of 0.92. Three or more attendances predicted need for transfusion with 60.0% sensitivity and 98.0% specificity. 74% of patients had at least one G&S sample taken pre-operatively, costing the trust approximately £3,800 per year in materials.

Conclusions

The findings of this study suggest that pre-operative G&S testing prior to cholecystectomy is not routinely required. Increased frequency of prior emergency hospital attendances with gallstone complications and co-morbidities associated with coagulopathies were pre-operative risk factors for post-operative blood transfusion. More selective testing could provide large financial savings for health institutions without compromising patient safety.

Plain Language Summary

Plain english summary

Many patients diagnosed with gallstones undergo surgery to remove their gallbladder. Blood tests are routinely performed in clinic before the operation, which may include testing a patient’s blood type in case of bleeding during or after the operation. This test is required before a patient receives a blood transfusion.

Testing the blood type of patients prior to gallbladder surgery may not be routinely required, as excessive bleeding from this operation is rare. Avoiding unnecessary blood tests protects patients from unwarranted needles, prevents delays to surgery and saves hospitals money. We therefore investigated how frequently patients undergoing gallbladder surgery in our unit have blood type testing. We also assessed how often patients require a blood transfusion and whether testing for blood type could have been safely performed once the need for transfusion was identified, instead of before the operation.

Looking back at 453 patients’ notes, we found that only five needed a blood transfusion within 30 days of their operation. None of these blood transfusions were needed on an emergency basis, and therefore there would have been enough time to test these patients for their blood type without having to test them before the operation. Despite this, nearly three-quarters of our patients had blood type testing before the operation. Each of these tests costs an estimated £11 per sample in our unit, and therefore £3,800 per year could have been saved were these tests not performed.

The five patients who required a transfusion were found to have attended hospital more times before their operation with problems related to gallstones. Therefore, our study provides evidence that performing gallbladder operations on a more urgent basis following an admission to hospital with gallstone complications could reduce a patients’ risk of bleeding.

Keywords

Blood transfusion, blood typing, cholecystectomy, crossmatching, gallstones, group and save, haemorrhage, type and save

Corresponding author: Michael G Fadel

Competing interests: No competing interests were disclosed.

Grant information: MGF is funded by the National Institute for Health and Care Research (NIHR) under a Doctoral Fellowship award (DF-R8-NIHR303043).The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Copyright: © 2024 O'Leary L et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How to cite: O'Leary L, Sherwood WB, Fadel MG and Barkeji M. Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study [version 2; peer review: 2 approved]. NIHR Open Res 2024, 4:17 (https://doi.org/10.3310/nihropenres.13543.2) First published: 05 Apr 2024, 4:17 (https://doi.org/10.3310/nihropenres.13543.1) Latest published: 23 Oct 2024, 4:17 (https://doi.org/10.3310/nihropenres.13543.2)

Revised Amendments from Version 1

This article has been revised following peer review. It now clearly states the retrospective nature of the study. We corrected the coding system used for patient identification, changing International Classification of Diseases to Office of Population Censuses and Surveys codes. The specific codes are now listed.
In Table 1, total and subtotal cholecystectomies have been separated under “Operation type.” The proportions of subtotal procedures in each group are discussed in the Results. The lack of association between transfusion and subtotal cholecystectomy is addressed in the Discussion.
The Methodology clarifies our management of patients with obstructive jaundice, ensuring that it is clear patients underwent bile duct clearance prior to cholecystectomy. Handling of missing body mass index data is explained, noting that univariate analysis could not be performed on the 31% of patients for whom data were missing.
For statistical analysis, Fisher’s exact test replaced Pearson’s χ2 test for categorical data, as it is more accurate with small group sizes. Updated p-values for Gender, ASA grade, comorbidities, indication for surgery, operative urgency, operation type and number of G&S samples did not affect which variables reached statistical significance, and therefore our conclusions were unaltered.
Figure 1 has been updated with a y-axis label.
We revised the discussion to note that many hospitals use uncrossmatched group O positive blood in individuals without childbearing potential, as highlighted by a reviewer.
The Discussion now includes a summary of our findings on the rarity of blood transfusion and addresses known inaccuracies in estimating intraoperative blood loss. We expanded the limitations section, particularly regarding the potential underpowering due to the small number of transfusions, and conclude by calling for UK guidelines to standardize preoperative testing.

See the authors' detailed response to the review by Yulia Lin
See the authors' detailed response to the review by Raimundas Lunevicius

Introduction

Pre-operative evaluation is an opportunity to assess and mitigate a patient’s risk of undergoing anaesthesia and surgery. Blood tests are a common component of this assessment and may include group and save (G&S) testing, which identifies a patient’s red blood cell type and screens for irregular antibodies. It has been suggested that G&S testing is overperformed prior to laparoscopic cholecystectomy and a targeted approach should be adopted^1–14. Yet the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing.

Guidelines published in 2016 by the UK National Institute for Health and Care Excellence (NICE) on pre-operative testing prior to elective surgery stratified patients by their co-morbidities and the complexity of the proposed surgery¹⁵. The aim was to standardise and avoid unnecessary investigations in low- and intermediate-risk operations, however the committee excluded from the scope of the guidelines specific advice relating to G&S testing. Guidelines provided by the French Society of Anaesthesiology and Intensive Care advise if the risk of bleeding or blood transfusion is perceived to be “nil to low”, G&S testing is unnecessary, whereas if it is “intermediate to high”, these tests should be performed¹⁶. However, they do not give specific advice as to which patient and operative factors should be considered as part of this risk assessment.

Choosing Wisely, an international campaign to reduce unnecessary investigations, published recommendations from the Canadian Society of Transfusion Medicine that included specific advice to avoid routine G&S testing in patients undergoing cholecystectomy, as transfusion rates among these patients are low¹⁷. This advice is infrequently heeded: we recently published a systematic review of the available literature relating to G&S testing in patients who underwent cholecystectomy¹. Over 460,000 patients were included, 37.8% of whom underwent pre-operative G&S testing. Peri-operative transfusions occurred in only 2.1% of patients, and the authors of all the studies included in the review recommended a more targeted approach to pre-operative G&S testing^1–14.

The decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics. For fully crossmatched blood to be issued in our unit, patients must have one G&S sample taken within the preceding five days, plus a second sample that can be of any age on the patient’s electronic health records. Without clear guidance, inexperienced staff may err on the side of over-investigation¹⁸. Many patients will have two samples taken pre-operatively due to the erroneous perception that this would decrease the time for crossmatched blood to be issued in the unlikely event of rapid intra-operative haemorrhage. As Ghirardo and his colleagues pointed out, such an event would demand rapid transfusion with uncrossmatched blood products, during which time G&S testing can be performed and crossmatched blood obtained within twenty minutes⁶. Even if G&S samples were taken pre-operatively, the crossmatching of blood products would take the same amount of time in this scenario.

Purported pre-operative risk factors for peri-operative blood transfusion in the available literature include anaemia, regular oral anticoagulant use, cardiovascular co-morbidities, type 2 diabetes mellitus, primary haematological malignancies and increased American Society of Anesthesiologists (ASA) grade^5,6,9,11,14. None of these authors have assessed whether these associations are independent predictors of blood transfusion.

NICE and international guidelines support urgent cholecystectomy over a planned, delayed operation in those presenting with acute biliary pathology (especially cholecystitis and gallstone pancreatitis), as it reduces length of hospital stay, medical costs, number of workdays lost, and prevents recurrent admissions whilst on a waiting list^19–22. A large population-based study in Canada showed patients with acute cholecystitis who were discharged without early cholecystectomy had a 14% chance of acute hospital attendance with gallbladder pathology within 6 weeks or 29% within a year²³. Despite this, there is great variability in inter-hospital practice regarding the proportion of cholecystectomies performed on an emergency basis²⁴. Repeated episodes of acute biliary pathology could increase operative difficulty, and hence increase the risk of bleeding and need for blood transfusion.

This study audited our unit’s peri-operative blood transfusion and G&S testing rates in patients undergoing cholecystectomy. It aimed to identify independent pre-operative risk factors that may predict peri-operative blood transfusion in these patients. We also hypothesised that the odds of transfusion could be predicted by the number of prior emergency attendances to hospital with acute biliary pathology secondary to gallstones. Armed with this, and with a greater understanding of local transfusion rates and the financial implications of routine G&S testing, we aim to improve selectivity of pre-operative G&S testing prior to this very common procedure.

Methods

Patient and public involvement

This project was born out of several informal discussions with patients pre-operatively. Some were found not to have two valid group and save samples on the mornings of their operations, and some senior members of the theatre team insisted the case could not go ahead until this had been rectified. We identified a lack of local or national guidance to advise on the matter, which led to variability in the specific blood tests taken at patients’ pre-operative clinic appointments. Many patients expressed frustration at the need to undergo additional venipuncture and at the delay to their operation until the blood tests had been taken. Occasionally these delays led to some patients staying overnight in hospital, despite their operations having been intended to be day-case procedures.

There was universal support from these patients for a project that would help to create a consensus on the pre-operative blood tests performed prior to routine elective surgery with low risk of blood transfusion. We are very grateful for sharing their comments and opinions with the authors of this study.

Study methodology

This retrospective cohort study analysed the electronic health records of 453 consecutive adult patients who underwent laparoscopic or open cholecystectomy between August 2019 and January 2021 in one NHS trust in London, UK. Both total and subtotal cholecystectomies were included. The trust comprises two large teaching hospitals, each with an accident and emergency department and a general surgical department.

A database was created by IT professionals in the local audit department, who identified patients by the following Office of Population Censuses and Surveys version 4 (OPCS-4) codes: J18.1 (Total cholecystectomy and excision of surrounding tissue), J18.3 (Total cholecystectomy NEC), J18.4 (Partial cholecystectomy and exploration of common bile duct), J18.5 (Partial cholecystectomy NEC), J18.8 (Other specified excision of gallbladder) and J18.9 (Unspecified excision of gallbladder). Patient notes – which are electronically linked to the transfusion laboratory information system– were analysed and cross-referenced with fluid balance charts for receipt of transfusion of packed red blood cells either intra-operatively or up to 30 days post-operatively.

For a patient to have two valid G&S samples pre-operatively, one sample would need to be taken within the preceding five days of their operation, and two samples if the patient did not have a prior G&S sample on their hospital electronic records. To provide a cost-analysis for the processing of pre-operative G&S samples, we present the number of G&S samples taken within five days of the operation. We have not included the cost of historic samples on patients’ electronic records.

Indication for surgery was defined as the diagnosis made at the patient’s last emergency hospital attendance, or from that stated on the patient’s latest general surgical clinic letter if that patient had no prior emergency attendances. Any patient who presented with obstructive jaundice was investigated with magnetic resonance cholangiopancreatography and, if required, underwent clearance of obstructing choledocholithiasis with endoscopic retrograde cholangiopancreatography prior to cholecystectomy. An emergency operation was defined as cholecystectomy undertaken during the same admission as an emergency attendance to the hospital; otherwise, the procedure was considered having been performed electively.

A patient was deemed to have cardiovascular co-morbidities if at least one of the following were recorded in the patient’s electronic health records: hypertension, ischaemic heart disease, peripheral vascular disease, atrial fibrillation, or cerebrovascular accident. Pre-operative haemoglobin was the most recent pre-operative blood test performed. For those who had their full blood count checked multiple times during the post-operative recovery, we have defined “post-operative haemoglobin” as the lowest value within 30 days of the operation. Estimated intra-operative blood loss was recorded by the operating surgeon in the operation note. If the surgeon had written “minimal” or similar, a value of 0 millilitres was assigned for the purpose of analysis.

Statistical analysis

Data analyses were performed using IBM SPSS Statistics v.28 (IBM, Armonk, New York, USA). A free software alternative is GNU PSPP v.2.0.0 (Free Software Foundation, Boston, Massachusetts, USA). Statistical analyses of categorical data were performed using Fisher’s exact test. Differences between numerical data were explored using the Mann-Whitney U test. A p-value less than 0.05 was considered statistically significant.

Binomial logistic regression determined whether the number of emergency attendances to the same hospital trust in the preceding three years with complications of gallstones predicted risk of requiring a red blood cell transfusion within 30 days of cholecystectomy independent of age, gender, urgency of operation, indication for surgery, ASA grade, presence of cardiovascular co-morbidities, type 2 diabetes mellitus, primary haematological malignancy, regular use of oral anticoagulants or antiplatelets, and pre-operative haemoglobin level. The Wald χ² test was used to determine statistical significance for each of the independent variables.

To assess further the power that frequency of emergency hospital attendances predicts post-operative blood transfusion, a receiver operating characteristic (ROC) curve was drawn. The area under the curve (AUC) represents the model's ability to distinguish between outcomes: the closer the AUC is to 1, the more accurately the model correctly classifies the outcomes based on its sensitivity and specificity.

Four hundred and thirty-nine patients (96.9%) had their pre-operative haemoglobin levels checked. One hundred and ninety-five patients (43.0%) had post-operative haemoglobin levels taken. Univariate analysis of pre- to post-operative haemoglobin change therefore excluded those patients who were missing these blood tests. The 14 patients with missing pre-operative haemoglobin levels were excluded from the regression model. Body mass index was not calculable in 139 patients (30.7%), who were missing height or weight from their electronic health records. Therefore, these patients were excluded from this univariate comparison between those who received a blood transfusion and those who did not. All other data recorded in this study were complete.

Statement of ethics

This study and its database were registered as a clinical audit and approved locally by the West Middlesex University Hospital audit department (audit registration number PCD935). All data were anonymised and collated as part of a clinical audit and therefore patient consent was not required.

Results

Our data have been made publicly available on Open Science Framework at https://osf.io/5uva4/²⁵.

Five of the 453 patients (1.1%) received a blood transfusion within 30 days of their operation. Table 1 summarises demographic characteristics of the patients, stratified by whether they received a blood transfusion. On univariate analysis, those who received a transfusion tended to be more co-morbid, as measured by ASA grade (p = 0.017). One patient in each group had an underlying primary haematological malignancy predisposing to bleeding, which was also found to be a risk factor associated with requiring a blood transfusion (p = 0.022): the patient who received a transfusion had myelodysplasia characterised by chronic anaemia and thrombocytopaenia. Similar rates of cardiovascular co-morbidities (p = 1.000) and type 2 diabetes mellitus (p = 0.458) were seen between the two groups.

Table 1. Patient demographics stratified by whether they received a blood transfusion.

Data are presented as number of patients, followed by the percentage of patients within that transfusion status group in brackets, unless specified otherwise. ASA, American Society of Anesthesiologists; G&S, Group and Save; Hb, Haemoglobin; IQR, InterQuartile Range; NA, Not Applicable; *Mann-Whitney U test. †Fisher’s exact test.

Demographic	Blood transfusion received	Blood transfusion not received	p-value
Patients, n (% of total)	5 (1.1)	448 (98.9)	NA
Median age, years (IQR)	59 (34 – 67)	50 (39 – 61)	0.703*
Gender Female Male	4 (80.0) 1 (20.0)	308 (68.8) 140 (31.3)	1.000^†
Median body mass index, kg/m² (IQR)	25 (24 – 31)	28 (25 – 32)	0.425*
ASA grade I II III IV V	1 (20.0) 3 (60.0) 0 (0.0) 1 (20.0) 0 (0.0)	128 (28.6) 272 (60.7) 48 (10.7) 0 (0.0) 0 (0.0)	0.017^†
Co-morbidities Cardiovascular Type 2 diabetes mellitus Primary haematological malignancy Regularly on oral anticoagulant or antiplatelet	1 (20.0) 1 (20.0) 1 (20.0) 0 (0.0)	134 (29.9) 51 (11.4) 1 (0.2) 33 (7.4)	1.000^† 0.458^† 0.022^† 1.000^†
Indication Biliary colic Acute cholecystitis Pancreatitis Obstructive jaundice Gallbladder polyps Empyema	1 (20.0) 3 (60.0) 0 (0.0) 1 (20.0) 0 (0.0) 0 (0.0)	217 (48.4) 132 (29.5) 45 (10.0) 27 (6.0) 12 (2.7) 15 (3.3)	0.301^†
Operative urgency Emergency Elective	1 (20.0) 4 (80.0)	80 (17.9) 368 (82.1)	1.000^†
Operation type Laparoscopic total cholecystectomy Laparoscopic subtotal cholecystectomy Laparoscopic converted to open total cholecystectomy Primary open total cholecystectomy	4 (80.0) 1 (20.0) 0 (0.0) 0 (0.0)	440 (98.1) 4 (0.9) 3 (0.7) 1 (0.2)	1.000^†
Median estimated intra-operative blood loss, ml (IQR)	0 (0 – 50)	0 (0 – 0)	0.056*
Median pre-operative Hb, g/l (IQR)	132 (121 – 145)	134 (126 – 143)	0.651*
Median change between pre- and post-operative Hb, g/l (IQR)	-36 (-68 – -35)	-8 (-14 – -2)	0.001*
Number of pre-operative G&S samples 0 1 2	0 (0.0) 1 (20.0) 4 (80.0)	116 (25.6) 178 (39.5) 154 (34.9)	0.152^†
Median length of hospital stay, days (IQR)	8 (5 – 12)	1 (0 – 2)	0.002*
Median number of prior emergency hospital attendances with complications of gallstones, n (IQR)	4 (2 – 4)	1 (0 – 1)	< 0.001*

There was no difference in intra-operative blood loss estimated by the operating surgeon between those who required a blood transfusion and those who did not. However, those patients requiring a blood transfusion had greater drops in post-operative haemoglobin (-36 g/l vs. -8 g/l, p = 0.001), despite starting with similar pre-operative haemoglobin levels (132 g/l vs. 134 g/l, p = 0.651). Blood transfusions were associated with longer inpatient stays (median 8 days vs. 1 day, p = 0.002).

Five procedures (1.1%) were subtotal cholecystectomies. All were undertaken laparoscopically; three on an emergency basis, and two were elective procedures. The indication for surgery for each of these patients was cholecystitis. One of the five patients who underwent subtotal cholecystectomy required a blood transfusion the day after the operation, though patients undergoing a subtotal, rather than total, cholecystectomy were not more likely to require a blood transfusion (p = 0.054).

The patient characteristics and indications for transfusion for each of the five cases who received a blood transfusion are detailed in the Supplementary Table, which can be found at https://osf.io/5uva4/²⁵. None required emergency group O uncrossmatched blood intra- or post-operatively. At the time of identification of the need for a blood transfusion, each patient was haemodynamically stable; as such, sufficient time would have been present for two G&S samples to be taken and for blood to be fully crossmatched prior to transfusion.

In 116 cases (25.6%), no G&S samples were taken in the preceding five days of the operation. One hundred and seventy-nine patients (39.5%) had one G&S sample taken and 158 (34.9%) had two. Three hundred and one of the 404 patients with ASA grade I or II had at least one G&S sample taken. The cost of analysing a G&S sample in our trust is £11, excluding laboratory staffing costs. Within our cohort, analysis of pre-operative G&S samples therefore cost in the region of £3,800 per year in materials.

Patients who required a peri-operative blood transfusion had more prior emergency hospital attendances in the preceding three years with gallstone complications (median 4 attendances vs. 1 attendance, p < 0.001). A logistic regression was performed to determine whether this association held independently of the effects of age, gender, urgency of operation, indication, ASA grade, presence of cardiovascular co-morbidities, type 2 diabetes mellitus, primary haematological malignancy, regular oral anticoagulant or antiplatelet use, or pre-operative haemoglobin level. The regression model was statistically significant (p = 0.042), explained 53.3% (Nagelkerke R²) of the variance in blood transfusion requirement and correctly classified 98.9% of cases. Following adjustment for the other co-variants, we found that with each additional emergency hospital attendance, the odds of requiring a blood transfusion increased by a factor of 4.6 (95% confidence interval 1.3 to 16.3, p = 0.019). No other co-variants added significantly to the model.

ROC curve analysis showed an AUC of 0.92 (95% confidence interval 0.79 – 1.00) for number of prior emergency hospital attendances as a predictor of the need for post-operative blood transfusion (Figure 1). Three or more prior attendances predicted those patients who would require a post-operative blood transfusion with 60.0% sensitivity and 98.0% specificity.

Figure 1. Receiver Operating Characteristic (ROC) curve analysis of number of prior emergency hospital attendances and its impact on the requirement for post-operative blood transfusion.

Area under the curve 0.92 (95% confidence interval 0.79 – 1.00).

Discussion

This study demonstrated that, at 1.1%, peri-operative blood transfusion following cholecystectomy in our cohort is rare, and comparable to that in the available literature^1–14. In all our cases, following identification of the need for peri-operative blood transfusion, there was enough time for two G&S samples to be taken and typed, and fully crossmatched blood procured, which corroborates the findings of other cohort studies^5,6,12. In the rare cases of intra-operative major vascular injury, it would be detrimental to the patient to await crossmatched blood, and therefore even with two valid G&S samples available, rapid transfusion of group O uncrossmatched blood would be required^1,6,12,14. G&S testing pre-operatively is therefore not required in most cases^1–14.

We found a strongly independent association between the number of pre-operative emergency attendances with acute gallstone complications and the need for a post-operative blood transfusion following cholecystectomy. Within our cohort, three or more emergency hospital attendances with biliary pathology was highly predictive of this outcome. It is likely that frequent flare-ups of biliary inflammation create more local fibrosis and adhesions, setting up a technically more challenging procedure, as was found in Lo and colleagues’ randomised trial of early versus delayed cholecystectomies²⁶. Fibrosis and oedema in chronic cholecystitis destroy clear operative planes between the gallbladder and the liver bed, which may increase the risk of bleeding from the raw liver surface²⁷. Increased vascular fragility and bleeding may result from the vascular congestion and angiogenesis associated with chronic inflammatory processes^27,28. Four of the 5 patients who required a blood transfusion in our cohort developed post-operative subhepatic haematomas. It may be that these cases were technically challenging, and therefore achieving adequate haemostasis was more difficult; or, even if haemostasis were achieved initially, a high risk of rebleeding followed abdominal closure.

In 1995, Nassar and colleagues published a grading system classifying laparoscopic cholecystectomies according to intra-operative technical difficulty, taking into consideration the density of adhesions and features of the gallbladder and cystic pedicle that make for a more complex dissection²⁹. Their team have shown that patients who undergo emergency laparoscopic cholecystectomy are more likely to have a higher grade of difficulty if they have had multiple hospital admissions with acute biliary disease compared to those for operated on in their first admission, and that a higher Nassar scale grade is associated with a higher risk of bleeding^30,31. Within our cohort, the indication for surgery for all five patients who underwent subtotal cholecystectomies was cholecystitis; three of whom were undergoing emergency procedures for the same. These findings reflect the operative challenges faced when attempting to safely dissect the hepatocystic triangle in a recurrently inflamed gallbladder. This study did not find an association between transfusion of blood products and a subtotal procedure; perhaps decisions to undertake a more conservative procedure were being made before significant bleeding complications occurred.

We found no contingency between estimated intra-operative blood loss and the need for a post-operative blood transfusion. Visual estimation of blood loss is most frequently used as it is quick and effortless, yet notoriously imprecise and poorly reproducible³². Blood collected by suction may be diluted by intra-peritoneal lavage and bile and estimates often do not consider blood contaminating gauze swabs. Accuracy may be improved by strictly measuring the amount of intra-abdominal wash used, and weighing contaminated materials, subtracting their dry weights. That blood loss estimated by the operating surgeon showed no correlation with need for transfusion reinforces the need for clinicians to be Cognisant that blood loss is frequently underestimated.

In one case (Case 3, Supplementary Table, https://osf.io/5uva4/²⁵), the need for post-operative blood transfusion was attributed to underlying primary haematological malignancy, though our regression model did not show that this was an independent predictor of transfusion. Others have also found primary haematological cancers to be a risk factor for peri-operative transfusion: in an observational study of 4,462 patients in Scotland, this co-morbidity was present in 6 of the 48 (12.5%) cases who required a blood transfusion¹¹. A single-centre retrospective study of 1,167 patients undergoing cholecystectomy in the USA also found that one of their five patients who required a peri-operative blood transfusion had a diagnosis of chronic leukaemia with thrombocytopaenia⁶. We also found an association between higher ASA grade and need for post-operative transfusion in cholecystectomy, confirming findings by other groups, though this association also did not hold through our regression model^9,11.

There are important limitations that must be considered when interpreting the study findings. Fortunately, blood transfusion is rarely required; as such, with only five patients in our cohort requiring this intervention, it is difficult to definitively exclude those pre-operative risk factors that failed to reach statistical significance due to underpowering. Nevertheless, we believe the relationship between number of acute episodes secondary to gallstone disease and post-operative complications is an important finding favouring performing cholecystectomies on an urgent basis^2,8,9,13. A meta-analysis of the published literature may help to confirm the associations between need for blood transfusion and other risk factors identified in other cohort studies, including pre-operative anaemia, obstructive jaundice as an indication for surgery, regular oral anticoagulant use, and underlying type 2 diabetes mellitus^5,6,9,11,14.

The introduction of national UK guidelines that provide recommendations on which patient and operative factors, based on the findings of this and the other studies discussed, would improve selectivity of G&S testing. This would help to prevent uncertainty among staff running pre-operative assessment clinics with regards to appropriate testing, standardise practice between units and avoid wasting of resources.

Conclusions

Our study suggests that routine G&S testing prior to cholecystectomy, despite this being common practice in many units, is not required. A more selective approach to pre-operative G&S testing can be safe and help save resources. We suggest criteria may include multiple prior emergency hospital attendances, high ASA grade and a history of haematological disorders. It can also be inferred that performing planned cholecystectomy on an urgent basis following emergency admission with acute biliary pathology should be considered where possible to avoid recurrent episodes, as the frequency of prior emergency hospital attendances with gallstone complications may potentially increase the risk of receiving post-operative blood transfusion.

Data availability

Underlying data

Open Science Framework: Underlying data for ‘Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study’, https://doi.org/10.17605/OSF.IO/5UVA4²⁵

Data are available under the terms of the Creative Commons Zero “No rights reserved” data waiver (CC0 1.0 Public domain dedication).

Faculty Opinions recommended

References

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5. Fong ML, Urriza Rodriguez D, Elberm H, et al.: Are type and screen samples routinely necessary before laparoscopic cholecystectomy? J Gastrointest Surg. 2021; 25(2): 447–51. PubMed Abstract | Publisher Full Text
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8. Hamza N, Pereira M, Gilliam A: Routine ‘group and save’ is unnecessary on the day of surgery for elective laparoscopic cholecystectomy. The Bulletin of the Royal College of Surgeons of England. 2015; 97(6): E1–4. Publisher Full Text
9. Li N, Low N: A closed-loop audit of routine pre-operative “type and screen” tests for laparoscopic cholecystectomy. Perioper Care Oper Room Manag. 2020; 21: 100141. Publisher Full Text
10. Lin JS, Chen YJ, Tzeng CH, et al.: Revisiting of preoperative blood ordering policy—a single institute’s experience in Taiwan. J Chin Med Assoc. 2006; 69(11): 507–11. PubMed Abstract | Publisher Full Text
11. Quinn M, Suttie S, Li A, et al.: Are blood group and save samples needed for cholecystectomy? Surg Endosc. 2011; 25(8): 2505–8. PubMed Abstract | Publisher Full Text
12. Tandon A, Shahzad K, Nunes Q, et al.: Routine preoperative blood group and save testing is unnecessary for elective laparoscopic cholecystectomy. J Ayub Med Coll Abbottabad. 2017; 29(3): 373–7. PubMed Abstract
13. Thomson PM, Ross J, Mukherjee S, et al.: Are routine blood group and save samples needed for laparoscopic day case surgery? World J Surg. 2016; 40(6): 1295–8. PubMed Abstract | Publisher Full Text
14. Usal H, Nabagiez J, Sayad P, et al.: Cost effectiveness of routine type and screen testing before laparoscopic cholecystectomy. Surg Endosc. 1999; 13(2): 146–7. PubMed Abstract | Publisher Full Text
15. National Institute for Health and Care Excellence: Routine preoperative tests for elective surgery: NICE guideline [NG45]. 2016; [cited 2023 Oct 17]. Reference Source
16. Molliex S, Pierre S, Bléry C, et al.: Examens préinterventionnels systématiques. Ann Fr Anesth Reanim. 2012; 31(9): 752–63. Reference Source
17. Canadian Society for Transfusion Medicine: Ten things physicians and patients should question. Choosing Wisely Canada, 2021; [cited 2023 Oct 17]. Reference Source
18. Patey AM, Islam R, Francis JJ, et al.: Anesthesiologists' and surgeons' perceptions about routine pre-operative testing in low-risk patients: application of the Theoretical Domains Framework (TDF) to identify factors that influence physicians' decisions to order pre-operative tests. Implement Sci. 2012; 7(1): 52. PubMed Abstract | Publisher Full Text | Free Full Text
19. National Institute for Health and Care Excellence: Gallstone disease: diagnosis and management: Clinical guideline [CG188]. 2014; [cited 2023 Oct 17]. Reference Source
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23. de Mestral C, Rotstein OD, Laupacis A, et al.: A population-based analysis of the clinical course of 10,304 patients with acute cholecystitis, discharged without cholecystectomy. J Trauma Acute Care Surg. 2013; 74(1): 26–30; discussion 30–1. PubMed Abstract | Publisher Full Text
24. CholeS Study Group, West Midlands Research Collaborative: Population-based cohort study of variation in the use of emergency cholecystectomy for benign gallbladder diseases. Br J Surg. 2016; 103(12): 1716–26. PubMed Abstract | Publisher Full Text
25. O’Leary L, Sherwood WB, Fadel M: Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study. Open Science Framework. [Dataset] 2024. http://www.doi.org/10.17605/OSF.IO/5UVA4
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Version 2

VERSION 2 PUBLISHED 05 Apr 2024

Author details Author details

Lawrence O'Leary
Roles: Conceptualization, Data Curation, Formal Analysis, Investigation, Methodology, Resources, Software, Writing – Original Draft Preparation, Writing – Review & Editing

William B Sherwood
Roles: Conceptualization, Data Curation, Formal Analysis, Investigation, Methodology, Resources, Writing – Review & Editing

Musa Barkeji
Roles: Conceptualization, Project Administration, Supervision, Visualization, Writing – Review & Editing

Competing interests

No competing interests were disclosed.

Grant information

MGF is funded by the National Institute for Health and Care Research (NIHR) under a Doctoral Fellowship award (DF-R8-NIHR303043).The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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O'Leary L, Sherwood WB, Fadel MG and Barkeji M. Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study [version 2; peer review: 2 approved]. NIHR Open Res 2024, 4:17 (https://doi.org/10.3310/nihropenres.13543.2)

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Reviewer Report 28 Oct 2024

Raimundas Lunevicius, Liverpool University Hospitals NHS Foundation Trust,, Lower Lane, Liverpool L9, UK

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Reviewer Report 25 Oct 2024

Yulia Lin, University of Toronto, Toronto, ON, Canada

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Reviewer Report 15 Sep 2024

Raimundas Lunevicius, Liverpool University Hospitals NHS Foundation Trust,, Lower Lane, Liverpool L9, UK

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https://doi.org/10.3310/nihropenres.14701.r31980

The authors defined the local audit project as a retrospective cohort study that explored the frequency of testing in the general surgery unit, rates of and independent pre-operative risk factors for peri-operative blood transfusion. The authors have decided to conduct this study because the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing, although it has been shown, between 1999 and 2022, that G&S testing is overperformed before laparoscopic cholecystectomy in various health care facilities of the UK, and, therefore, a targeted approach should be adopted. The authors also emphasised that the decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics, i.e. on local resources and standard operative procedures.

Purported pre-operative risk factors for peri-operative blood transfusion in the available literature include anaemia, regular oral anticoagulant use, cardiovascular co-morbidities, type 2 diabetes mellitus, primary haematological malignancies and increased American Society of Anesthesiologists (ASA) Grade. Whether these associations are independent predictors (incl. primary haematological malignancies) of blood transfusion is unclear.

Therefore, the study aimed to identify independent pre-operative risk factors that may predict peri-operative blood transfusion in these patients. The authors correctly hypothesised (every gallbladder surgeon knows that) that the odds of transfusion could be predicted by the number of prior emergency attendances to the hospital with acute biliary pathology secondary to gallstones. In this regard, they are proud to be the first (the phrase “we are the first” used) to explore this association, adding a unique perspective to the existing literature.

Methods

Study methodology. I find that ’this cross-sectional study analysed 453 consecutive adult patients’. On the other hand, this study suggests that patients’ electronic hospital records were analysed to extract and abstract the information into data points. Please consider rephrasing.
I find ‘Patients aged under 16 years were not included in the study’. Please specify (section ‘Results’) how many patients you have excluded’. If none, please delete this phrase. In addition, ‘patients aged under 16 years’. Is it a correct writing?
Patients were identified by their International Classification of Diseases, 10th revision codes. This is unspecific writing. It remains unclear how this was done: by the authors or IT professionals. Also, ICD-10 codes could have been provided clearly (please do it). I am writing this because methods and data should be well-described so that they can be replicated and/or combined in different settings. That is a fundamental FAIR principle, https://www.go-fair.org/fair-principles/.
The paragraph “Length of hospital stay referred to the number of post-operative days during the admission in which the operation took place. It did not include any prior admissions nor post-operative readmissions.” The second sentence is highly unusual. I would recommend deleting it.
Re “Estimated intra-operative blood loss was recorded by the operating surgeon in the operation note.” It is the most inaccurate and most diseased method of estimation of blood loss. It needs to be discussed in ‘Discussion’.
Re ‘post-operative haemoglobin was the lowest value within 30 days of the operation’. I don’t understand it (the lowest value). Please clarify.
I find the phrase ‘All other data recorded in this study were complete.’ However, the Open Science Framework at https://osf.io/5uva4/ shows that this is not the case. Many empty cells within the Excel database (for example, cell H2, cell H29, Cell h44, etc.) indicate that not all data recordings in this study were completed. Please consider this point seriously and update the Open Science Framework accordingly (it is a pretty problematic task; you will need to communicate with the administrator of the Open Science Framework as a new dataset will generate a new DOI).
Statistical analysis. It would be useful to understand why the authors have shown the number of degrees of freedom in brackets. Please add the sentence and explain to the readers (including the patients and public) what that would mean – one degree of freedom or another. I say ‘the patients and public’ because the first subsection of Methods concerns the patients and public. For example, what does it mean (χ2 (3) = 90.3, p < 0.001)? I mean χ2 (3) = 90.3.
I find that ‘Statistical analyses of categorical data were performed using Pearson’s chi-squared test. Also, I find the comparisons between 2 subgroups - n= 5 and n= 448. Please explain in the methods why you had chosen the chi-squared test instead of the exact Fisher’s test when one of the subgroups included only 5 patients. Would you consider conducting a new analysis with a more precise test in use?
The area under the curve (AUC) can be used to visualise the sensitivity and specificity of a model predicting a certain outcome: the closer the AUC is to 1. That is correct; however, why do the authors use the verb form ‘can be’? The authors ‘used to visualise’ (not ‘can be used to visualise’). Please revise the paper from an academic language point of view.

Results

I find 28 patients with obstructive jaundice (1 + 27, Table 1). This has not been said in Methods. Please clarify.
It is unusual to see no subtotal cholecystectomies in > 453 patients with such indications for surgery. Please provide a comment (Discussion). The source: Lunevicius R, et al., 2022 [Ref-1]
Figure 1. Please specify Y-axis (Sensitivity)
The phrase ‘statistically significant is old-fashioned. Please speak about associations in your paper (you did it in Discussion – excellent writing)
I find the ‘Supplementary Table’. This needs to be linked to the Supplementary Table source online.

Discussion

Please avoid writing this kind of ‘we are the first to demonstrate’. It doesn’t look good (especially in the context of your paper). Others will decide who is the first or the second (a higher Nassar scale grade is associated with a higher risk of bleeding)
Future prospective national studies with a larger sample size are required to further assess whether G&S routine testing is required and its associated safety. So, I am inclined to say that prospective national studies are unnecessary in light of references 1 – 14 and the results and findings of this study.
The point (rationale of the study) mentioned in the Introduction (“The authors have decided to conduct this study because the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing, although it has been shown, between 1999 and 2022, that G&S testing is overperformed before laparoscopic cholecystectomy in various health care facilities of the UK, and, therefore, a targeted approach should be adopted. The authors also emphasised that the decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics, i.e. on local resources and standard operative procedures) and requires discussion in light of the findings of this study.

Is the work clearly and accurately presented and does it cite the current literature?

Yes
Is the study design appropriate and is the work technically sound?

Yes
Are sufficient details of methods and analysis provided to allow replication by others?

Partly
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Yes

References

1. Lunevicius R, Nzenwa IC, Mesri M: A nationwide analysis of gallbladder surgery in England between 2000 and 2019.Surgery. 2022; 171 (2): 276-284 PubMed Abstract | Publisher Full Text

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Gallbaldder surgery, subtotal cholecystectomy, emergency laparotomy, hernia, global health

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

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Author Response 23 Oct 2024

Lawrence O'Leary, Department of General Surgery, West Middlesex University Hospital, London, TW7 6AF, UK

23 Oct 2024

Author Response
Dear Mr Lunevicius,

Thank you for taking the time to read our manuscript. We really appreciate your advice and helpful suggestions to improve the paper. We have responded to ... Continue reading
Dear Mr Lunevicius,

Thank you for taking the time to read our manuscript. We really appreciate your advice and helpful suggestions to improve the paper. We have responded to each of your comments in turn below, and hope you approve of our changes.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

Methods

Study methodology. I find that ’this cross-sectional study analysed 453 consecutive adult patients’. On the other hand, this study suggests that patients’ electronic hospital records were analysed to extract and abstract the information into data points. Please consider rephrasing.

Thank you. We have rephrased the beginning of the section so it more clearly specifies that it was a retrospective cohort study analysing patients’ electronic health records.

I find ‘Patients aged under 16 years were not included in the study’. Please specify (section ‘Results’) how many patients you have excluded’. If none, please delete this phrase. In addition, ‘patients aged under 16 years’. Is it a correct writing?

As you suggest, we have deleted this sentence. We have said the analysis was of adult patients in the first paragraph. No patients were excluded from the analysis.

Patients were identified by their International Classification of Diseases, 10th revision codes. This is unspecific writing. It remains unclear how this was done: by the authors or IT professionals. Also, ICD-10 codes could have been provided clearly (please do it). I am writing this because methods and data should be well-described so that they can be replicated and/or combined in different settings. That is a fundamental FAIR principle, https://www.go-fair.org/fair-principles/.

Thank you. The database was created by IT professionals from the local audit department and sent to the authors. What was assumed to be ICD-10 codes were, in fact, OPCS-4 procedure codes. We have now specified this in the second paragraph of the section with the codes they used to compile the list of patients. We apologise for this error.

The paragraph “Length of hospital stay referred to the number of post-operative days during the admission in which the operation took place. It did not include any prior admissions nor post-operative readmissions.” The second sentence is highly unusual. I would recommend deleting it.

We have deleted the paragraph.

Re “Estimated intra-operative blood loss was recorded by the operating surgeon in the operation note.” It is the most inaccurate and most diseased method of estimation of blood loss. It needs to be discussed in ‘Discussion’.

Thank you. We included this, as visual estimation is the most commonly used method of estimating and recording intraoperative blood loss. As you kindly suggest, we have added a paragraph highlighting its inaccuracy, and that our study reinforces that surgeons’ perceived blood loss does not correlate with risk of needing transfusion.

Re ‘post-operative haemoglobin was the lowest value within 30 days of the operation’. I don’t understand it (the lowest value). Please clarify.

Several patients had post-operative blood tests taken on multiple occasions. If this was the case, for the sake of our analysis, we defined “post-operative haemoglobin” as the lowest haemoglobin level. We have clarified this in the manuscript.

I find the phrase ‘All other data recorded in this study were complete.’ However, the Open Science Framework at https://osf.io/5uva4/ shows that this is not the case. Many empty cells within the Excel database (for example, cell H2, cell H29, Cell h44, etc.) indicate that not all data recordings in this study were completed. Please consider this point seriously and update the Open Science Framework accordingly (it is a pretty problematic task; you will need to communicate with the administrator of the Open Science Framework as a new dataset will generate a new DOI).

Thank you. We sincerely apologise for this inaccuracy. We have updated the manuscript under “Statistical analysis” to highlight the missing values in pre- and post-operative haemoglobin and body mass index, and explained how we have managed these in our analyses.

Statistical analysis. It would be useful to understand why the authors have shown the number of degrees of freedom in brackets. Please add the sentence and explain to the readers (including the patients and public) what that would mean – one degree of freedom or another. I say ‘the patients and public’ because the first subsection of Methods concerns the patients and public. For example, what does it mean (χ2 (3) = 90.3, p < 0.001)? I mean χ2 (3) = 90.3.

Thank you. After some deliberation, we have decided that showing the chi-squared values and degrees of freedom are complicating the readability of the manuscript without adding value to the messages we are trying to get across. We have therefore opted to exclude these and keep the p-values only.

I find that ‘Statistical analyses of categorical data were performed using Pearson’s chi-squared test. Also, I find the comparisons between 2 subgroups - n= 5 and n= 448. Please explain in the methods why you had chosen the chi-squared test instead of the exact Fisher’s test when one of the subgroups included only 5 patients. Would you consider conducting a new analysis with a more precise test in use?

Thank you. You are quite right that the Fisher’s exact test would have been more accurate for the analysis of categorical data. We have re-run the analyses for all those comparisons in which we had previously used Pearson’s chi-squared tests. We have updated the methodology and p-values in Table 1, in the body of the Results section and the Abstract accordingly. Those results that were previously statistically significant with Pearson’s chi-squared held as being statistically significant using Fisher’s; and those that did not reach statistically significance remained insignificant.

The area under the curve (AUC) can be used to visualise the sensitivity and specificity of a model predicting a certain outcome: the closer the AUC is to 1. That is correct; however, why do the authors use the verb form ‘can be’? The authors ‘used to visualise’ (not ‘can be used to visualise’). Please revise the paper from an academic language point of view.

Thank you. This sentence has been changed to “The area under the curve (AUC) represents the model's ability to distinguish between outcomes: the closer the AUC is to 1, the more accurately the model classifies the outcomes based on its sensitivity and specificity.”

Results

I find 28 patients with obstructive jaundice (1 + 27, Table 1). This has not been said in Methods. Please clarify.

These 28 patients comprised 19 patients who underwent elective cholecystectomy and 9 emergency “hot” operations. They all presented with obstructive jaundice and were investigated with MRCP and, if choledocholithiasis was confirmed, underwent removal of common bile duct stones with ERCP. Only after the CBD had been cleared did the patients undergo cholecystectomy. To clarify this, in the Methods section, we have added the following sentence: “Any patient who presented with obstructive jaundice was investigated with magnetic resonance cholangiopancreatography and, if required, underwent clearance of obstructing choledocholithiasis with endoscopic retrograde cholangiopancreatography prior to cholecystectomy.”

It is unusual to see no subtotal cholecystectomies in > 453 patients with such indications for surgery. Please provide a comment (Discussion). The source: Lunevicius R, et al., 2022 [Ref-1]

In our results, we did not divide the procedures into total and subtotal procedures; rather, we described the operative approach as laparoscopic, open or converted, anticipating that the size of incision and need to convert might contribute to the risk of blood loss and therefore need for transfusion. For clarity, we have relooked at the operation undertaken, and identified that 5 patients (1%) underwent subtotal procedures, all completed laparoscopically, and have added these to the “Operation type” heading in Table 1. We have added this as a new heading in the available data and reuploaded to the Open Science Framework, as well as adding a paragraph to the Results table. Patients who had a subtotal, rather than total, cholecystectomy were not more likely to receive a blood transfusion in our cohort. We have discussed these findings in the paragraph related to Nassar’s grading system and the association between operative difficulty increasing risk of bleeding.

Figure 1. Please specify Y-axis (Sensitivity)

Thank you. The y-axis label was inadvertently missed out. This has been reuploaded with the axis title.

The phrase ‘statistically significant is old-fashioned. Please speak about associations in your paper (you did it in Discussion – excellent writing)

Thank you for this advice. We have changed the phrasing when this occurred.

I find the ‘Supplementary Table’. This needs to be linked to the Supplementary Table source online.

Thank you. We have added the URL to our Open Science Framework project following mentions of the Supplementary Table. Here can be found both the Supplementary Table and our anonymised data.

Discussion

Please avoid writing this kind of ‘we are the first to demonstrate’. It doesn’t look good (especially in the context of your paper). Others will decide who is the first or the second (a higher Nassar scale grade is associated with a higher risk of bleeding)

Thank you, we have removed this on your advice.

Future prospective national studies with a larger sample size are required to further assess whether G&S routine testing is required and its associated safety. So, I am inclined to say that prospective national studies are unnecessary in light of references 1 – 14 and the results and findings of this study.

We have rephrased our concluding paragraph in the Discussion.

The point (rationale of the study) mentioned in the Introduction (“The authors have decided to conduct this study because the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing, although it has been shown, between 1999 and 2022, that G&S testing is overperformed before laparoscopic cholecystectomy in various health care facilities of the UK, and, therefore, a targeted approach should be adopted. The authors also emphasised that the decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics, i.e. on local resources and standard operative procedures) and requires discussion in light of the findings of this study.

Thank you, we have now brought our Discussion back round to the need for explicit national guidelines to help standardise G&S testing based on our findings and those of other studies.
Dear Mr Lunevicius,

Thank you for taking the time to read our manuscript. We really appreciate your advice and helpful suggestions to improve the paper. We have responded to each of your comments in turn below, and hope you approve of our changes.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

Methods

Study methodology. I find that ’this cross-sectional study analysed 453 consecutive adult patients’. On the other hand, this study suggests that patients’ electronic hospital records were analysed to extract and abstract the information into data points. Please consider rephrasing.

Thank you. We have rephrased the beginning of the section so it more clearly specifies that it was a retrospective cohort study analysing patients’ electronic health records.

I find ‘Patients aged under 16 years were not included in the study’. Please specify (section ‘Results’) how many patients you have excluded’. If none, please delete this phrase. In addition, ‘patients aged under 16 years’. Is it a correct writing?

As you suggest, we have deleted this sentence. We have said the analysis was of adult patients in the first paragraph. No patients were excluded from the analysis.

Patients were identified by their International Classification of Diseases, 10th revision codes. This is unspecific writing. It remains unclear how this was done: by the authors or IT professionals. Also, ICD-10 codes could have been provided clearly (please do it). I am writing this because methods and data should be well-described so that they can be replicated and/or combined in different settings. That is a fundamental FAIR principle, https://www.go-fair.org/fair-principles/.

Thank you. The database was created by IT professionals from the local audit department and sent to the authors. What was assumed to be ICD-10 codes were, in fact, OPCS-4 procedure codes. We have now specified this in the second paragraph of the section with the codes they used to compile the list of patients. We apologise for this error.

The paragraph “Length of hospital stay referred to the number of post-operative days during the admission in which the operation took place. It did not include any prior admissions nor post-operative readmissions.” The second sentence is highly unusual. I would recommend deleting it.

We have deleted the paragraph.

Re “Estimated intra-operative blood loss was recorded by the operating surgeon in the operation note.” It is the most inaccurate and most diseased method of estimation of blood loss. It needs to be discussed in ‘Discussion’.

Thank you. We included this, as visual estimation is the most commonly used method of estimating and recording intraoperative blood loss. As you kindly suggest, we have added a paragraph highlighting its inaccuracy, and that our study reinforces that surgeons’ perceived blood loss does not correlate with risk of needing transfusion.

Re ‘post-operative haemoglobin was the lowest value within 30 days of the operation’. I don’t understand it (the lowest value). Please clarify.

Several patients had post-operative blood tests taken on multiple occasions. If this was the case, for the sake of our analysis, we defined “post-operative haemoglobin” as the lowest haemoglobin level. We have clarified this in the manuscript.

I find the phrase ‘All other data recorded in this study were complete.’ However, the Open Science Framework at https://osf.io/5uva4/ shows that this is not the case. Many empty cells within the Excel database (for example, cell H2, cell H29, Cell h44, etc.) indicate that not all data recordings in this study were completed. Please consider this point seriously and update the Open Science Framework accordingly (it is a pretty problematic task; you will need to communicate with the administrator of the Open Science Framework as a new dataset will generate a new DOI).

Thank you. We sincerely apologise for this inaccuracy. We have updated the manuscript under “Statistical analysis” to highlight the missing values in pre- and post-operative haemoglobin and body mass index, and explained how we have managed these in our analyses.

Statistical analysis. It would be useful to understand why the authors have shown the number of degrees of freedom in brackets. Please add the sentence and explain to the readers (including the patients and public) what that would mean – one degree of freedom or another. I say ‘the patients and public’ because the first subsection of Methods concerns the patients and public. For example, what does it mean (χ2 (3) = 90.3, p < 0.001)? I mean χ2 (3) = 90.3.

Thank you. After some deliberation, we have decided that showing the chi-squared values and degrees of freedom are complicating the readability of the manuscript without adding value to the messages we are trying to get across. We have therefore opted to exclude these and keep the p-values only.

I find that ‘Statistical analyses of categorical data were performed using Pearson’s chi-squared test. Also, I find the comparisons between 2 subgroups - n= 5 and n= 448. Please explain in the methods why you had chosen the chi-squared test instead of the exact Fisher’s test when one of the subgroups included only 5 patients. Would you consider conducting a new analysis with a more precise test in use?

Thank you. You are quite right that the Fisher’s exact test would have been more accurate for the analysis of categorical data. We have re-run the analyses for all those comparisons in which we had previously used Pearson’s chi-squared tests. We have updated the methodology and p-values in Table 1, in the body of the Results section and the Abstract accordingly. Those results that were previously statistically significant with Pearson’s chi-squared held as being statistically significant using Fisher’s; and those that did not reach statistically significance remained insignificant.

The area under the curve (AUC) can be used to visualise the sensitivity and specificity of a model predicting a certain outcome: the closer the AUC is to 1. That is correct; however, why do the authors use the verb form ‘can be’? The authors ‘used to visualise’ (not ‘can be used to visualise’). Please revise the paper from an academic language point of view.

Thank you. This sentence has been changed to “The area under the curve (AUC) represents the model's ability to distinguish between outcomes: the closer the AUC is to 1, the more accurately the model classifies the outcomes based on its sensitivity and specificity.”

Results

I find 28 patients with obstructive jaundice (1 + 27, Table 1). This has not been said in Methods. Please clarify.

These 28 patients comprised 19 patients who underwent elective cholecystectomy and 9 emergency “hot” operations. They all presented with obstructive jaundice and were investigated with MRCP and, if choledocholithiasis was confirmed, underwent removal of common bile duct stones with ERCP. Only after the CBD had been cleared did the patients undergo cholecystectomy. To clarify this, in the Methods section, we have added the following sentence: “Any patient who presented with obstructive jaundice was investigated with magnetic resonance cholangiopancreatography and, if required, underwent clearance of obstructing choledocholithiasis with endoscopic retrograde cholangiopancreatography prior to cholecystectomy.”

It is unusual to see no subtotal cholecystectomies in > 453 patients with such indications for surgery. Please provide a comment (Discussion). The source: Lunevicius R, et al., 2022 [Ref-1]

In our results, we did not divide the procedures into total and subtotal procedures; rather, we described the operative approach as laparoscopic, open or converted, anticipating that the size of incision and need to convert might contribute to the risk of blood loss and therefore need for transfusion. For clarity, we have relooked at the operation undertaken, and identified that 5 patients (1%) underwent subtotal procedures, all completed laparoscopically, and have added these to the “Operation type” heading in Table 1. We have added this as a new heading in the available data and reuploaded to the Open Science Framework, as well as adding a paragraph to the Results table. Patients who had a subtotal, rather than total, cholecystectomy were not more likely to receive a blood transfusion in our cohort. We have discussed these findings in the paragraph related to Nassar’s grading system and the association between operative difficulty increasing risk of bleeding.

Figure 1. Please specify Y-axis (Sensitivity)

Thank you. The y-axis label was inadvertently missed out. This has been reuploaded with the axis title.

The phrase ‘statistically significant is old-fashioned. Please speak about associations in your paper (you did it in Discussion – excellent writing)

Thank you for this advice. We have changed the phrasing when this occurred.

I find the ‘Supplementary Table’. This needs to be linked to the Supplementary Table source online.

Thank you. We have added the URL to our Open Science Framework project following mentions of the Supplementary Table. Here can be found both the Supplementary Table and our anonymised data.

Discussion

Please avoid writing this kind of ‘we are the first to demonstrate’. It doesn’t look good (especially in the context of your paper). Others will decide who is the first or the second (a higher Nassar scale grade is associated with a higher risk of bleeding)

Thank you, we have removed this on your advice.

Future prospective national studies with a larger sample size are required to further assess whether G&S routine testing is required and its associated safety. So, I am inclined to say that prospective national studies are unnecessary in light of references 1 – 14 and the results and findings of this study.

We have rephrased our concluding paragraph in the Discussion.

The point (rationale of the study) mentioned in the Introduction (“The authors have decided to conduct this study because the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing, although it has been shown, between 1999 and 2022, that G&S testing is overperformed before laparoscopic cholecystectomy in various health care facilities of the UK, and, therefore, a targeted approach should be adopted. The authors also emphasised that the decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics, i.e. on local resources and standard operative procedures) and requires discussion in light of the findings of this study.

Thank you, we have now brought our Discussion back round to the need for explicit national guidelines to help standardise G&S testing based on our findings and those of other studies.
Competing Interests: We have no competing interests to declare. Close
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Respond or Comment

COMMENTS ON THIS REPORT

Author Response 23 Oct 2024

Lawrence O'Leary, Department of General Surgery, West Middlesex University Hospital, London, TW7 6AF, UK

23 Oct 2024

Author Response
Dear Mr Lunevicius,

Thank you for taking the time to read our manuscript. We really appreciate your advice and helpful suggestions to improve the paper. We have responded to ... Continue reading
Dear Mr Lunevicius,

Thank you for taking the time to read our manuscript. We really appreciate your advice and helpful suggestions to improve the paper. We have responded to each of your comments in turn below, and hope you approve of our changes.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

Methods

Study methodology. I find that ’this cross-sectional study analysed 453 consecutive adult patients’. On the other hand, this study suggests that patients’ electronic hospital records were analysed to extract and abstract the information into data points. Please consider rephrasing.

Thank you. We have rephrased the beginning of the section so it more clearly specifies that it was a retrospective cohort study analysing patients’ electronic health records.

I find ‘Patients aged under 16 years were not included in the study’. Please specify (section ‘Results’) how many patients you have excluded’. If none, please delete this phrase. In addition, ‘patients aged under 16 years’. Is it a correct writing?

As you suggest, we have deleted this sentence. We have said the analysis was of adult patients in the first paragraph. No patients were excluded from the analysis.

Patients were identified by their International Classification of Diseases, 10th revision codes. This is unspecific writing. It remains unclear how this was done: by the authors or IT professionals. Also, ICD-10 codes could have been provided clearly (please do it). I am writing this because methods and data should be well-described so that they can be replicated and/or combined in different settings. That is a fundamental FAIR principle, https://www.go-fair.org/fair-principles/.

Thank you. The database was created by IT professionals from the local audit department and sent to the authors. What was assumed to be ICD-10 codes were, in fact, OPCS-4 procedure codes. We have now specified this in the second paragraph of the section with the codes they used to compile the list of patients. We apologise for this error.

The paragraph “Length of hospital stay referred to the number of post-operative days during the admission in which the operation took place. It did not include any prior admissions nor post-operative readmissions.” The second sentence is highly unusual. I would recommend deleting it.

We have deleted the paragraph.

Re “Estimated intra-operative blood loss was recorded by the operating surgeon in the operation note.” It is the most inaccurate and most diseased method of estimation of blood loss. It needs to be discussed in ‘Discussion’.

Thank you. We included this, as visual estimation is the most commonly used method of estimating and recording intraoperative blood loss. As you kindly suggest, we have added a paragraph highlighting its inaccuracy, and that our study reinforces that surgeons’ perceived blood loss does not correlate with risk of needing transfusion.

Re ‘post-operative haemoglobin was the lowest value within 30 days of the operation’. I don’t understand it (the lowest value). Please clarify.

Several patients had post-operative blood tests taken on multiple occasions. If this was the case, for the sake of our analysis, we defined “post-operative haemoglobin” as the lowest haemoglobin level. We have clarified this in the manuscript.

I find the phrase ‘All other data recorded in this study were complete.’ However, the Open Science Framework at https://osf.io/5uva4/ shows that this is not the case. Many empty cells within the Excel database (for example, cell H2, cell H29, Cell h44, etc.) indicate that not all data recordings in this study were completed. Please consider this point seriously and update the Open Science Framework accordingly (it is a pretty problematic task; you will need to communicate with the administrator of the Open Science Framework as a new dataset will generate a new DOI).

Thank you. We sincerely apologise for this inaccuracy. We have updated the manuscript under “Statistical analysis” to highlight the missing values in pre- and post-operative haemoglobin and body mass index, and explained how we have managed these in our analyses.

Statistical analysis. It would be useful to understand why the authors have shown the number of degrees of freedom in brackets. Please add the sentence and explain to the readers (including the patients and public) what that would mean – one degree of freedom or another. I say ‘the patients and public’ because the first subsection of Methods concerns the patients and public. For example, what does it mean (χ2 (3) = 90.3, p < 0.001)? I mean χ2 (3) = 90.3.

Thank you. After some deliberation, we have decided that showing the chi-squared values and degrees of freedom are complicating the readability of the manuscript without adding value to the messages we are trying to get across. We have therefore opted to exclude these and keep the p-values only.

I find that ‘Statistical analyses of categorical data were performed using Pearson’s chi-squared test. Also, I find the comparisons between 2 subgroups - n= 5 and n= 448. Please explain in the methods why you had chosen the chi-squared test instead of the exact Fisher’s test when one of the subgroups included only 5 patients. Would you consider conducting a new analysis with a more precise test in use?

Thank you. You are quite right that the Fisher’s exact test would have been more accurate for the analysis of categorical data. We have re-run the analyses for all those comparisons in which we had previously used Pearson’s chi-squared tests. We have updated the methodology and p-values in Table 1, in the body of the Results section and the Abstract accordingly. Those results that were previously statistically significant with Pearson’s chi-squared held as being statistically significant using Fisher’s; and those that did not reach statistically significance remained insignificant.

The area under the curve (AUC) can be used to visualise the sensitivity and specificity of a model predicting a certain outcome: the closer the AUC is to 1. That is correct; however, why do the authors use the verb form ‘can be’? The authors ‘used to visualise’ (not ‘can be used to visualise’). Please revise the paper from an academic language point of view.

Thank you. This sentence has been changed to “The area under the curve (AUC) represents the model's ability to distinguish between outcomes: the closer the AUC is to 1, the more accurately the model classifies the outcomes based on its sensitivity and specificity.”

Results

I find 28 patients with obstructive jaundice (1 + 27, Table 1). This has not been said in Methods. Please clarify.

These 28 patients comprised 19 patients who underwent elective cholecystectomy and 9 emergency “hot” operations. They all presented with obstructive jaundice and were investigated with MRCP and, if choledocholithiasis was confirmed, underwent removal of common bile duct stones with ERCP. Only after the CBD had been cleared did the patients undergo cholecystectomy. To clarify this, in the Methods section, we have added the following sentence: “Any patient who presented with obstructive jaundice was investigated with magnetic resonance cholangiopancreatography and, if required, underwent clearance of obstructing choledocholithiasis with endoscopic retrograde cholangiopancreatography prior to cholecystectomy.”

It is unusual to see no subtotal cholecystectomies in > 453 patients with such indications for surgery. Please provide a comment (Discussion). The source: Lunevicius R, et al., 2022 [Ref-1]

In our results, we did not divide the procedures into total and subtotal procedures; rather, we described the operative approach as laparoscopic, open or converted, anticipating that the size of incision and need to convert might contribute to the risk of blood loss and therefore need for transfusion. For clarity, we have relooked at the operation undertaken, and identified that 5 patients (1%) underwent subtotal procedures, all completed laparoscopically, and have added these to the “Operation type” heading in Table 1. We have added this as a new heading in the available data and reuploaded to the Open Science Framework, as well as adding a paragraph to the Results table. Patients who had a subtotal, rather than total, cholecystectomy were not more likely to receive a blood transfusion in our cohort. We have discussed these findings in the paragraph related to Nassar’s grading system and the association between operative difficulty increasing risk of bleeding.

Figure 1. Please specify Y-axis (Sensitivity)

Thank you. The y-axis label was inadvertently missed out. This has been reuploaded with the axis title.

The phrase ‘statistically significant is old-fashioned. Please speak about associations in your paper (you did it in Discussion – excellent writing)

Thank you for this advice. We have changed the phrasing when this occurred.

I find the ‘Supplementary Table’. This needs to be linked to the Supplementary Table source online.

Thank you. We have added the URL to our Open Science Framework project following mentions of the Supplementary Table. Here can be found both the Supplementary Table and our anonymised data.

Discussion

Please avoid writing this kind of ‘we are the first to demonstrate’. It doesn’t look good (especially in the context of your paper). Others will decide who is the first or the second (a higher Nassar scale grade is associated with a higher risk of bleeding)

Thank you, we have removed this on your advice.

Future prospective national studies with a larger sample size are required to further assess whether G&S routine testing is required and its associated safety. So, I am inclined to say that prospective national studies are unnecessary in light of references 1 – 14 and the results and findings of this study.

We have rephrased our concluding paragraph in the Discussion.

The point (rationale of the study) mentioned in the Introduction (“The authors have decided to conduct this study because the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing, although it has been shown, between 1999 and 2022, that G&S testing is overperformed before laparoscopic cholecystectomy in various health care facilities of the UK, and, therefore, a targeted approach should be adopted. The authors also emphasised that the decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics, i.e. on local resources and standard operative procedures) and requires discussion in light of the findings of this study.

Thank you, we have now brought our Discussion back round to the need for explicit national guidelines to help standardise G&S testing based on our findings and those of other studies.
Dear Mr Lunevicius,

Thank you for taking the time to read our manuscript. We really appreciate your advice and helpful suggestions to improve the paper. We have responded to each of your comments in turn below, and hope you approve of our changes.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

Methods

Study methodology. I find that ’this cross-sectional study analysed 453 consecutive adult patients’. On the other hand, this study suggests that patients’ electronic hospital records were analysed to extract and abstract the information into data points. Please consider rephrasing.

Thank you. We have rephrased the beginning of the section so it more clearly specifies that it was a retrospective cohort study analysing patients’ electronic health records.

I find ‘Patients aged under 16 years were not included in the study’. Please specify (section ‘Results’) how many patients you have excluded’. If none, please delete this phrase. In addition, ‘patients aged under 16 years’. Is it a correct writing?

As you suggest, we have deleted this sentence. We have said the analysis was of adult patients in the first paragraph. No patients were excluded from the analysis.

Patients were identified by their International Classification of Diseases, 10th revision codes. This is unspecific writing. It remains unclear how this was done: by the authors or IT professionals. Also, ICD-10 codes could have been provided clearly (please do it). I am writing this because methods and data should be well-described so that they can be replicated and/or combined in different settings. That is a fundamental FAIR principle, https://www.go-fair.org/fair-principles/.

Thank you. The database was created by IT professionals from the local audit department and sent to the authors. What was assumed to be ICD-10 codes were, in fact, OPCS-4 procedure codes. We have now specified this in the second paragraph of the section with the codes they used to compile the list of patients. We apologise for this error.

The paragraph “Length of hospital stay referred to the number of post-operative days during the admission in which the operation took place. It did not include any prior admissions nor post-operative readmissions.” The second sentence is highly unusual. I would recommend deleting it.

We have deleted the paragraph.

Re “Estimated intra-operative blood loss was recorded by the operating surgeon in the operation note.” It is the most inaccurate and most diseased method of estimation of blood loss. It needs to be discussed in ‘Discussion’.

Thank you. We included this, as visual estimation is the most commonly used method of estimating and recording intraoperative blood loss. As you kindly suggest, we have added a paragraph highlighting its inaccuracy, and that our study reinforces that surgeons’ perceived blood loss does not correlate with risk of needing transfusion.

Re ‘post-operative haemoglobin was the lowest value within 30 days of the operation’. I don’t understand it (the lowest value). Please clarify.

Several patients had post-operative blood tests taken on multiple occasions. If this was the case, for the sake of our analysis, we defined “post-operative haemoglobin” as the lowest haemoglobin level. We have clarified this in the manuscript.

I find the phrase ‘All other data recorded in this study were complete.’ However, the Open Science Framework at https://osf.io/5uva4/ shows that this is not the case. Many empty cells within the Excel database (for example, cell H2, cell H29, Cell h44, etc.) indicate that not all data recordings in this study were completed. Please consider this point seriously and update the Open Science Framework accordingly (it is a pretty problematic task; you will need to communicate with the administrator of the Open Science Framework as a new dataset will generate a new DOI).

Thank you. We sincerely apologise for this inaccuracy. We have updated the manuscript under “Statistical analysis” to highlight the missing values in pre- and post-operative haemoglobin and body mass index, and explained how we have managed these in our analyses.

Statistical analysis. It would be useful to understand why the authors have shown the number of degrees of freedom in brackets. Please add the sentence and explain to the readers (including the patients and public) what that would mean – one degree of freedom or another. I say ‘the patients and public’ because the first subsection of Methods concerns the patients and public. For example, what does it mean (χ2 (3) = 90.3, p < 0.001)? I mean χ2 (3) = 90.3.

Thank you. After some deliberation, we have decided that showing the chi-squared values and degrees of freedom are complicating the readability of the manuscript without adding value to the messages we are trying to get across. We have therefore opted to exclude these and keep the p-values only.

I find that ‘Statistical analyses of categorical data were performed using Pearson’s chi-squared test. Also, I find the comparisons between 2 subgroups - n= 5 and n= 448. Please explain in the methods why you had chosen the chi-squared test instead of the exact Fisher’s test when one of the subgroups included only 5 patients. Would you consider conducting a new analysis with a more precise test in use?

Thank you. You are quite right that the Fisher’s exact test would have been more accurate for the analysis of categorical data. We have re-run the analyses for all those comparisons in which we had previously used Pearson’s chi-squared tests. We have updated the methodology and p-values in Table 1, in the body of the Results section and the Abstract accordingly. Those results that were previously statistically significant with Pearson’s chi-squared held as being statistically significant using Fisher’s; and those that did not reach statistically significance remained insignificant.

The area under the curve (AUC) can be used to visualise the sensitivity and specificity of a model predicting a certain outcome: the closer the AUC is to 1. That is correct; however, why do the authors use the verb form ‘can be’? The authors ‘used to visualise’ (not ‘can be used to visualise’). Please revise the paper from an academic language point of view.

Thank you. This sentence has been changed to “The area under the curve (AUC) represents the model's ability to distinguish between outcomes: the closer the AUC is to 1, the more accurately the model classifies the outcomes based on its sensitivity and specificity.”

Results

I find 28 patients with obstructive jaundice (1 + 27, Table 1). This has not been said in Methods. Please clarify.

These 28 patients comprised 19 patients who underwent elective cholecystectomy and 9 emergency “hot” operations. They all presented with obstructive jaundice and were investigated with MRCP and, if choledocholithiasis was confirmed, underwent removal of common bile duct stones with ERCP. Only after the CBD had been cleared did the patients undergo cholecystectomy. To clarify this, in the Methods section, we have added the following sentence: “Any patient who presented with obstructive jaundice was investigated with magnetic resonance cholangiopancreatography and, if required, underwent clearance of obstructing choledocholithiasis with endoscopic retrograde cholangiopancreatography prior to cholecystectomy.”

It is unusual to see no subtotal cholecystectomies in > 453 patients with such indications for surgery. Please provide a comment (Discussion). The source: Lunevicius R, et al., 2022 [Ref-1]

In our results, we did not divide the procedures into total and subtotal procedures; rather, we described the operative approach as laparoscopic, open or converted, anticipating that the size of incision and need to convert might contribute to the risk of blood loss and therefore need for transfusion. For clarity, we have relooked at the operation undertaken, and identified that 5 patients (1%) underwent subtotal procedures, all completed laparoscopically, and have added these to the “Operation type” heading in Table 1. We have added this as a new heading in the available data and reuploaded to the Open Science Framework, as well as adding a paragraph to the Results table. Patients who had a subtotal, rather than total, cholecystectomy were not more likely to receive a blood transfusion in our cohort. We have discussed these findings in the paragraph related to Nassar’s grading system and the association between operative difficulty increasing risk of bleeding.

Figure 1. Please specify Y-axis (Sensitivity)

Thank you. The y-axis label was inadvertently missed out. This has been reuploaded with the axis title.

The phrase ‘statistically significant is old-fashioned. Please speak about associations in your paper (you did it in Discussion – excellent writing)

Thank you for this advice. We have changed the phrasing when this occurred.

I find the ‘Supplementary Table’. This needs to be linked to the Supplementary Table source online.

Thank you. We have added the URL to our Open Science Framework project following mentions of the Supplementary Table. Here can be found both the Supplementary Table and our anonymised data.

Discussion

Please avoid writing this kind of ‘we are the first to demonstrate’. It doesn’t look good (especially in the context of your paper). Others will decide who is the first or the second (a higher Nassar scale grade is associated with a higher risk of bleeding)

Thank you, we have removed this on your advice.

Future prospective national studies with a larger sample size are required to further assess whether G&S routine testing is required and its associated safety. So, I am inclined to say that prospective national studies are unnecessary in light of references 1 – 14 and the results and findings of this study.

We have rephrased our concluding paragraph in the Discussion.

The point (rationale of the study) mentioned in the Introduction (“The authors have decided to conduct this study because the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing, although it has been shown, between 1999 and 2022, that G&S testing is overperformed before laparoscopic cholecystectomy in various health care facilities of the UK, and, therefore, a targeted approach should be adopted. The authors also emphasised that the decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics, i.e. on local resources and standard operative procedures) and requires discussion in light of the findings of this study.

Thank you, we have now brought our Discussion back round to the need for explicit national guidelines to help standardise G&S testing based on our findings and those of other studies.
Competing Interests: We have no competing interests to declare. Close
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Reviewer Report 10 Jun 2024

Yulia Lin, University of Toronto, Toronto, ON, Canada

Approved with Reservations

https://doi.org/10.3310/nihropenres.14701.r31977

Thank you for the opportunity to review this well-written manuscript. This is a retrospective audit of 453 patients undergoing cholecystectomy at two teaching hospitals over 18 months. The authors found that despite 74% of patients having a preoperative group and save (G&S) performed in the 5 days prior to surgery, only 5 pts (1.1%) required a blood transfusion. These transfusions were non-urgent and occurred postoperatively where there would have been adequate time to perform a G&S. Logistic regression demonstrated an association between prior emergency attendance. Univariable analyses showed an association of underlying haematological malignancy and higher ASA with blood transfusion that was not present in logistic regression. The cost of the unnecessary G&S tests was £3800 per year.

There are clarifications that would be helpful to the reader:

Methods

Please clarify that this was a “retrospective” cross-sectional study.
Please clarify whether transfusion data were obtained from the electronic record linked to the transfusion laboratory information system as chart records that are not linked can be inaccurate.
This is a comment for the authors’ institution. Many institutions allow a group and save to be done within 30 days of the procedure (rather than only 5 days) provided that the patient has not received a transfusion or been pregnant in the 3 months prior. This may increase efficiency for patients who do require a G&S.

Results

Please clarify the hospital policy for type of blood for emergency uncrossmatched blood. Most institutions would provide group O positive blood and only group O negative to individuals of childbearing potential. Depending on the hospital policy, the text should be revised to group O uncrossmatched blood. This change is suggested to avoid the common misconception that only group O negative can be given in an emergency uncrossmatched scenario. (This also applies to the reference to group O negative in the Discussion).
Please clarify if the cost of the preoperative G&S tests includes only the ASA grade I and II patients or all G&S done preoperatively for this cohort.
In the logistic regression, the only independent factor that was associated with perioperative blood transfusion was prior emergency hospital attendance. It should be stated that the association of higher ASA and hematological malignancy was only seen in univariable analysis in the Abstract.

Discussion

The primary question of the study was the frequency of G&S testing and perioperative blood transfusion as noted in the first sentence of the conclusion. Suggest that paragraph 6 of the Discussion be the first paragraph summarizing the main findings of the study.
While the association of previous emergency attendance was noted in this study, the sample size of events (patients who received a blood transfusion) is only 5. Any statistical associations found (or not found) are limited given that there are so few events. Please add this major limitation.

Conclusion

Because patients who has prior emergency attendance had greater risk of blood transfusion, does not necessarily translate to those patients requiring surgery on their emergency attendance. Suggest de-emphasizing this inference. (This also applies to the final paragraph in the Plain English summary)
It would be reasonable to suggest potential criteria for G&S e.g. prior emergency hospital attendance, higher ASA and known history of haematological malignancy.

Is the work clearly and accurately presented and does it cite the current literature?

Yes
Is the study design appropriate and is the work technically sound?

Yes
Are sufficient details of methods and analysis provided to allow replication by others?

Yes
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Partly

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Transfusion Medicine clinical practice, education and quality improvement

CITE

Report a concern

Author Response 23 Oct 2024

Lawrence O'Leary, Department of General Surgery, West Middlesex University Hospital, London, TW7 6AF, UK

23 Oct 2024

Author Response

Dear Dr Lin,
We really appreciate you taking the time to review our article and thank you for your expertise and advice on how we can make our messages clearer. ... Continue reading Dear Dr Lin,
We really appreciate you taking the time to review our article and thank you for your expertise and advice on how we can make our messages clearer. We have responded to each of your suggested clarifications in turn below.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

1. Reviewer: Methods - Please clarify that this was a “retrospective” cross-sectional study.
Author Response: Thank you – we have added this important detail to both the main manuscript Methods section and the abstract.

2. Reviewer: Please clarify whether transfusion data were obtained from the electronic record linked to the transfusion laboratory information system as chart records that are not linked can be inaccurate.
Author Response: In our institution, the patient electronic records are automatically updated with product type and volume by the transfusion laboratory when blood products are released to the wards. We primarily used this information to identify when blood products were prescribed, and confirmed these were administered by cross-referencing patient fluid balance charts. We have clarified this in the Methods section as you kindly suggest.

3. Reviewer: This is a comment for the authors’ institution. Many institutions allow a group and save to be done within 30 days of the procedure (rather than only 5 days) provided that the patient has not received a transfusion or been pregnant in the 3 months prior. This may increase efficiency for patients who do require a G&S.
Author Response: Thank you for this comment. We have checked with our transfusion laboratory, and confirmed they allow group and saves within 30 days of the procedure provided the same criteria you list are met. We have fed this back to our department.

4. Reviewer: Results - Please clarify the hospital policy for type of blood for emergency uncross matched blood. Most institutions would provide group O positive blood and only group O negative to individuals of childbearing potential. Depending on the hospital policy, the text should be revised to group O uncross matched blood. This change is suggested to avoid the common misconception that only group O negative can be given in an emergency uncross matched scenario. (This also applies to the reference to group O negative in the Discussion).
Author Response: We have confirmed this is the case in our unit and as per our national British Society for Haematology guidelines and corrected the manuscript accordingly.

5. Reviewer: Please clarify if the cost of the preoperative G&S tests includes only the ASA grade I and II patients or all G&S done preoperatively for this cohort.
Author Response: The costing was for the whole cohort, and we have amended this to make this clearer.

6. Reviewer: In the logistic regression, the only independent factor that was associated with perioperative blood transfusion was prior emergency hospital attendance. It should be stated that the association of higher ASA and hematological malignancy was only seen in univariable analysis in the Abstract.
Author Response: Thank you – this has been clarified in the Abstract.

7. Reviewer: Discussion - The primary question of the study was the frequency of G&S testing and perioperative blood transfusion as noted in the first sentence of the conclusion. Suggest that paragraph 6 of the Discussion be the first paragraph summarizing the main findings of the study.
Author Response: We agree with this suggestion, and have rearranged the Discussion section as per your advice.

8. Reviewer: While the association of previous emergency attendance was noted in this study, the sample size of events (patients who received a blood transfusion) is only 5. Any statistical associations found (or not found) are limited given that there are so few events. Please add this major limitation.
Author Response: Thank you – we have made the Limitations paragraph clearer to reflect this.

9. Reviewer: Conclusion - Because patients who has prior emergency attendance had greater risk of blood transfusion, does not necessarily translate to those patients requiring surgery on their emergency attendance. Suggest de-emphasizing this inference. (This also applies to the final paragraph in the Plain English summary)
Author Response: Our intention was not to infer that these patients should necessarily have a “hot” emergency cholecystectomy; rather, that these elective operations should be treated as urgent, and delays to operations avoided. We have therefore clarified this in the Plain English summary and Conclusion by adding that delays to planned operations should be avoided.

10. Reviewer: It would be reasonable to suggest potential criteria for G&S e.g. prior emergency hospital attendance, higher ASA and known history of haematological malignancy.
Author Response: Thank you, we have added this suggestion.
Dear Dr Lin,
We really appreciate you taking the time to review our article and thank you for your expertise and advice on how we can make our messages clearer. We have responded to each of your suggested clarifications in turn below.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

1. Reviewer: Methods - Please clarify that this was a “retrospective” cross-sectional study.
Author Response: Thank you – we have added this important detail to both the main manuscript Methods section and the abstract.

2. Reviewer: Please clarify whether transfusion data were obtained from the electronic record linked to the transfusion laboratory information system as chart records that are not linked can be inaccurate.
Author Response: In our institution, the patient electronic records are automatically updated with product type and volume by the transfusion laboratory when blood products are released to the wards. We primarily used this information to identify when blood products were prescribed, and confirmed these were administered by cross-referencing patient fluid balance charts. We have clarified this in the Methods section as you kindly suggest.

3. Reviewer: This is a comment for the authors’ institution. Many institutions allow a group and save to be done within 30 days of the procedure (rather than only 5 days) provided that the patient has not received a transfusion or been pregnant in the 3 months prior. This may increase efficiency for patients who do require a G&S.
Author Response: Thank you for this comment. We have checked with our transfusion laboratory, and confirmed they allow group and saves within 30 days of the procedure provided the same criteria you list are met. We have fed this back to our department.

4. Reviewer: Results - Please clarify the hospital policy for type of blood for emergency uncross matched blood. Most institutions would provide group O positive blood and only group O negative to individuals of childbearing potential. Depending on the hospital policy, the text should be revised to group O uncross matched blood. This change is suggested to avoid the common misconception that only group O negative can be given in an emergency uncross matched scenario. (This also applies to the reference to group O negative in the Discussion).
Author Response: We have confirmed this is the case in our unit and as per our national British Society for Haematology guidelines and corrected the manuscript accordingly.

5. Reviewer: Please clarify if the cost of the preoperative G&S tests includes only the ASA grade I and II patients or all G&S done preoperatively for this cohort.
Author Response: The costing was for the whole cohort, and we have amended this to make this clearer.

6. Reviewer: In the logistic regression, the only independent factor that was associated with perioperative blood transfusion was prior emergency hospital attendance. It should be stated that the association of higher ASA and hematological malignancy was only seen in univariable analysis in the Abstract.
Author Response: Thank you – this has been clarified in the Abstract.

7. Reviewer: Discussion - The primary question of the study was the frequency of G&S testing and perioperative blood transfusion as noted in the first sentence of the conclusion. Suggest that paragraph 6 of the Discussion be the first paragraph summarizing the main findings of the study.
Author Response: We agree with this suggestion, and have rearranged the Discussion section as per your advice.

8. Reviewer: While the association of previous emergency attendance was noted in this study, the sample size of events (patients who received a blood transfusion) is only 5. Any statistical associations found (or not found) are limited given that there are so few events. Please add this major limitation.
Author Response: Thank you – we have made the Limitations paragraph clearer to reflect this.

9. Reviewer: Conclusion - Because patients who has prior emergency attendance had greater risk of blood transfusion, does not necessarily translate to those patients requiring surgery on their emergency attendance. Suggest de-emphasizing this inference. (This also applies to the final paragraph in the Plain English summary)
Author Response: Our intention was not to infer that these patients should necessarily have a “hot” emergency cholecystectomy; rather, that these elective operations should be treated as urgent, and delays to operations avoided. We have therefore clarified this in the Plain English summary and Conclusion by adding that delays to planned operations should be avoided.

10. Reviewer: It would be reasonable to suggest potential criteria for G&S e.g. prior emergency hospital attendance, higher ASA and known history of haematological malignancy.
Author Response: Thank you, we have added this suggestion.
Competing Interests: We have no competing interests to declare. Close
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Author Response 23 Oct 2024

Lawrence O'Leary, Department of General Surgery, West Middlesex University Hospital, London, TW7 6AF, UK

23 Oct 2024

Author Response

Dear Dr Lin,
We really appreciate you taking the time to review our article and thank you for your expertise and advice on how we can make our messages clearer. ... Continue reading Dear Dr Lin,
We really appreciate you taking the time to review our article and thank you for your expertise and advice on how we can make our messages clearer. We have responded to each of your suggested clarifications in turn below.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

1. Reviewer: Methods - Please clarify that this was a “retrospective” cross-sectional study.
Author Response: Thank you – we have added this important detail to both the main manuscript Methods section and the abstract.

2. Reviewer: Please clarify whether transfusion data were obtained from the electronic record linked to the transfusion laboratory information system as chart records that are not linked can be inaccurate.
Author Response: In our institution, the patient electronic records are automatically updated with product type and volume by the transfusion laboratory when blood products are released to the wards. We primarily used this information to identify when blood products were prescribed, and confirmed these were administered by cross-referencing patient fluid balance charts. We have clarified this in the Methods section as you kindly suggest.

3. Reviewer: This is a comment for the authors’ institution. Many institutions allow a group and save to be done within 30 days of the procedure (rather than only 5 days) provided that the patient has not received a transfusion or been pregnant in the 3 months prior. This may increase efficiency for patients who do require a G&S.
Author Response: Thank you for this comment. We have checked with our transfusion laboratory, and confirmed they allow group and saves within 30 days of the procedure provided the same criteria you list are met. We have fed this back to our department.

4. Reviewer: Results - Please clarify the hospital policy for type of blood for emergency uncross matched blood. Most institutions would provide group O positive blood and only group O negative to individuals of childbearing potential. Depending on the hospital policy, the text should be revised to group O uncross matched blood. This change is suggested to avoid the common misconception that only group O negative can be given in an emergency uncross matched scenario. (This also applies to the reference to group O negative in the Discussion).
Author Response: We have confirmed this is the case in our unit and as per our national British Society for Haematology guidelines and corrected the manuscript accordingly.

5. Reviewer: Please clarify if the cost of the preoperative G&S tests includes only the ASA grade I and II patients or all G&S done preoperatively for this cohort.
Author Response: The costing was for the whole cohort, and we have amended this to make this clearer.

6. Reviewer: In the logistic regression, the only independent factor that was associated with perioperative blood transfusion was prior emergency hospital attendance. It should be stated that the association of higher ASA and hematological malignancy was only seen in univariable analysis in the Abstract.
Author Response: Thank you – this has been clarified in the Abstract.

7. Reviewer: Discussion - The primary question of the study was the frequency of G&S testing and perioperative blood transfusion as noted in the first sentence of the conclusion. Suggest that paragraph 6 of the Discussion be the first paragraph summarizing the main findings of the study.
Author Response: We agree with this suggestion, and have rearranged the Discussion section as per your advice.

8. Reviewer: While the association of previous emergency attendance was noted in this study, the sample size of events (patients who received a blood transfusion) is only 5. Any statistical associations found (or not found) are limited given that there are so few events. Please add this major limitation.
Author Response: Thank you – we have made the Limitations paragraph clearer to reflect this.

9. Reviewer: Conclusion - Because patients who has prior emergency attendance had greater risk of blood transfusion, does not necessarily translate to those patients requiring surgery on their emergency attendance. Suggest de-emphasizing this inference. (This also applies to the final paragraph in the Plain English summary)
Author Response: Our intention was not to infer that these patients should necessarily have a “hot” emergency cholecystectomy; rather, that these elective operations should be treated as urgent, and delays to operations avoided. We have therefore clarified this in the Plain English summary and Conclusion by adding that delays to planned operations should be avoided.

10. Reviewer: It would be reasonable to suggest potential criteria for G&S e.g. prior emergency hospital attendance, higher ASA and known history of haematological malignancy.
Author Response: Thank you, we have added this suggestion.
Dear Dr Lin,
We really appreciate you taking the time to review our article and thank you for your expertise and advice on how we can make our messages clearer. We have responded to each of your suggested clarifications in turn below.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

1. Reviewer: Methods - Please clarify that this was a “retrospective” cross-sectional study.
Author Response: Thank you – we have added this important detail to both the main manuscript Methods section and the abstract.

2. Reviewer: Please clarify whether transfusion data were obtained from the electronic record linked to the transfusion laboratory information system as chart records that are not linked can be inaccurate.
Author Response: In our institution, the patient electronic records are automatically updated with product type and volume by the transfusion laboratory when blood products are released to the wards. We primarily used this information to identify when blood products were prescribed, and confirmed these were administered by cross-referencing patient fluid balance charts. We have clarified this in the Methods section as you kindly suggest.

3. Reviewer: This is a comment for the authors’ institution. Many institutions allow a group and save to be done within 30 days of the procedure (rather than only 5 days) provided that the patient has not received a transfusion or been pregnant in the 3 months prior. This may increase efficiency for patients who do require a G&S.
Author Response: Thank you for this comment. We have checked with our transfusion laboratory, and confirmed they allow group and saves within 30 days of the procedure provided the same criteria you list are met. We have fed this back to our department.

4. Reviewer: Results - Please clarify the hospital policy for type of blood for emergency uncross matched blood. Most institutions would provide group O positive blood and only group O negative to individuals of childbearing potential. Depending on the hospital policy, the text should be revised to group O uncross matched blood. This change is suggested to avoid the common misconception that only group O negative can be given in an emergency uncross matched scenario. (This also applies to the reference to group O negative in the Discussion).
Author Response: We have confirmed this is the case in our unit and as per our national British Society for Haematology guidelines and corrected the manuscript accordingly.

5. Reviewer: Please clarify if the cost of the preoperative G&S tests includes only the ASA grade I and II patients or all G&S done preoperatively for this cohort.
Author Response: The costing was for the whole cohort, and we have amended this to make this clearer.

6. Reviewer: In the logistic regression, the only independent factor that was associated with perioperative blood transfusion was prior emergency hospital attendance. It should be stated that the association of higher ASA and hematological malignancy was only seen in univariable analysis in the Abstract.
Author Response: Thank you – this has been clarified in the Abstract.

7. Reviewer: Discussion - The primary question of the study was the frequency of G&S testing and perioperative blood transfusion as noted in the first sentence of the conclusion. Suggest that paragraph 6 of the Discussion be the first paragraph summarizing the main findings of the study.
Author Response: We agree with this suggestion, and have rearranged the Discussion section as per your advice.

8. Reviewer: While the association of previous emergency attendance was noted in this study, the sample size of events (patients who received a blood transfusion) is only 5. Any statistical associations found (or not found) are limited given that there are so few events. Please add this major limitation.
Author Response: Thank you – we have made the Limitations paragraph clearer to reflect this.

9. Reviewer: Conclusion - Because patients who has prior emergency attendance had greater risk of blood transfusion, does not necessarily translate to those patients requiring surgery on their emergency attendance. Suggest de-emphasizing this inference. (This also applies to the final paragraph in the Plain English summary)
Author Response: Our intention was not to infer that these patients should necessarily have a “hot” emergency cholecystectomy; rather, that these elective operations should be treated as urgent, and delays to operations avoided. We have therefore clarified this in the Plain English summary and Conclusion by adding that delays to planned operations should be avoided.

10. Reviewer: It would be reasonable to suggest potential criteria for G&S e.g. prior emergency hospital attendance, higher ASA and known history of haematological malignancy.
Author Response: Thank you, we have added this suggestion.
Competing Interests: We have no competing interests to declare. Close
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Version 2

VERSION 2 PUBLISHED 05 Apr 2024

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Version 2 (revision) 23 Oct 24	read	read
Version 1 05 Apr 24	read	read

Yulia Lin, University of Toronto, Toronto, ON, Canada
Raimundas Lunevicius, Liverpool University Hospitals NHS Foundation Trust,, Lower Lane, Liverpool L9, UK

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Reviewer Report

5 Views

28 Oct 2024 | for Version 2

Raimundas Lunevicius, Liverpool University Hospitals NHS Foundation Trust,, Lower Lane, Liverpool L9, UK

5 Views Cite this report Responses(0)

Approved

Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study. Version 2.

Dear Authors,

The revision of the manuscript has addressed the concerns raised, and questions asked. It significantly enhanced the clarity and quality of the article’s content.

I am pleased that your manuscript has been accepted for indexing without any reservations.

Your data are publicly available on Open Science Framework at https://osf.io/5uva4/, which is a real strength of the paper. It makes the study transparent and replicable according to FAIR Principles—GO FAIR.

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Gallbaldder surgery, subtotal cholecystectomy, emergency laparotomy, hernia, global health

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

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Reviewer Report

7 Views

25 Oct 2024 | for Version 2

Yulia Lin, University of Toronto, Toronto, ON, Canada

7 Views Cite this report Responses(0)

Approved

The authors have addressed my comments. No further comments.

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Transfusion Medicine clinical practice, education and quality improvement

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

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Reviewer Report

20 Views

15 Sep 2024 | for Version 1

Raimundas Lunevicius, Liverpool University Hospitals NHS Foundation Trust,, Lower Lane, Liverpool L9, UK

20 Views Cite this report Responses(1)

Approved With Reservations

Study methodology. I find that ’this cross-sectional study analysed 453 consecutive adult patients’. On the other hand, this study suggests that patients’ electronic hospital records were analysed to extract and abstract the information into data points. Please consider rephrasing.
I find ‘Patients aged under 16 years were not included in the study’. Please specify (section ‘Results’) how many patients you have excluded’. If none, please delete this phrase. In addition, ‘patients aged under 16 years’. Is it a correct writing?
Patients were identified by their International Classification of Diseases, 10th revision codes. This is unspecific writing. It remains unclear how this was done: by the authors or IT professionals. Also, ICD-10 codes could have been provided clearly (please do it). I am writing this because methods and data should be well-described so that they can be replicated and/or combined in different settings. That is a fundamental FAIR principle, https://www.go-fair.org/fair-principles/.
The paragraph “Length of hospital stay referred to the number of post-operative days during the admission in which the operation took place. It did not include any prior admissions nor post-operative readmissions.” The second sentence is highly unusual. I would recommend deleting it.
Re “Estimated intra-operative blood loss was recorded by the operating surgeon in the operation note.” It is the most inaccurate and most diseased method of estimation of blood loss. It needs to be discussed in ‘Discussion’.
Re ‘post-operative haemoglobin was the lowest value within 30 days of the operation’. I don’t understand it (the lowest value). Please clarify.
I find the phrase ‘All other data recorded in this study were complete.’ However, the Open Science Framework at https://osf.io/5uva4/ shows that this is not the case. Many empty cells within the Excel database (for example, cell H2, cell H29, Cell h44, etc.) indicate that not all data recordings in this study were completed. Please consider this point seriously and update the Open Science Framework accordingly (it is a pretty problematic task; you will need to communicate with the administrator of the Open Science Framework as a new dataset will generate a new DOI).
Statistical analysis. It would be useful to understand why the authors have shown the number of degrees of freedom in brackets. Please add the sentence and explain to the readers (including the patients and public) what that would mean – one degree of freedom or another. I say ‘the patients and public’ because the first subsection of Methods concerns the patients and public. For example, what does it mean (χ2 (3) = 90.3, p < 0.001)? I mean χ2 (3) = 90.3.
I find that ‘Statistical analyses of categorical data were performed using Pearson’s chi-squared test. Also, I find the comparisons between 2 subgroups - n= 5 and n= 448. Please explain in the methods why you had chosen the chi-squared test instead of the exact Fisher’s test when one of the subgroups included only 5 patients. Would you consider conducting a new analysis with a more precise test in use?
The area under the curve (AUC) can be used to visualise the sensitivity and specificity of a model predicting a certain outcome: the closer the AUC is to 1. That is correct; however, why do the authors use the verb form ‘can be’? The authors ‘used to visualise’ (not ‘can be used to visualise’). Please revise the paper from an academic language point of view.

Results

I find 28 patients with obstructive jaundice (1 + 27, Table 1). This has not been said in Methods. Please clarify.
It is unusual to see no subtotal cholecystectomies in > 453 patients with such indications for surgery. Please provide a comment (Discussion). The source: Lunevicius R, et al., 2022 [Ref-1]
Figure 1. Please specify Y-axis (Sensitivity)
The phrase ‘statistically significant is old-fashioned. Please speak about associations in your paper (you did it in Discussion – excellent writing)
I find the ‘Supplementary Table’. This needs to be linked to the Supplementary Table source online.

Discussion

Please avoid writing this kind of ‘we are the first to demonstrate’. It doesn’t look good (especially in the context of your paper). Others will decide who is the first or the second (a higher Nassar scale grade is associated with a higher risk of bleeding)
Future prospective national studies with a larger sample size are required to further assess whether G&S routine testing is required and its associated safety. So, I am inclined to say that prospective national studies are unnecessary in light of references 1 – 14 and the results and findings of this study.
The point (rationale of the study) mentioned in the Introduction (“The authors have decided to conduct this study because the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing, although it has been shown, between 1999 and 2022, that G&S testing is overperformed before laparoscopic cholecystectomy in various health care facilities of the UK, and, therefore, a targeted approach should be adopted. The authors also emphasised that the decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics, i.e. on local resources and standard operative procedures) and requires discussion in light of the findings of this study.

Is the work clearly and accurately presented and does it cite the current literature?

Yes
Is the study design appropriate and is the work technically sound?

Yes
Are sufficient details of methods and analysis provided to allow replication by others?

Partly
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Yes

References

1. Lunevicius R, Nzenwa IC, Mesri M: A nationwide analysis of gallbladder surgery in England between 2000 and 2019.Surgery. 2022; 171 (2): 276-284 PubMed Abstract | Publisher Full Text

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Gallbaldder surgery, subtotal cholecystectomy, emergency laparotomy, hernia, global health

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Responses (1)

Author Response

23 Oct 2024

Lawrence O'Leary, Department of General Surgery, West Middlesex University Hospital, London, TW7 6AF, UK

Dear Mr Lunevicius,

Thank you for taking the time to read our manuscript. We really appreciate your advice and helpful suggestions to improve the paper. We have responded to each of your comments in turn below, and hope you approve of our changes.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

Methods

Study methodology. I find that ’this cross-sectional study analysed 453 consecutive adult patients’. On the other hand, this study suggests that patients’ electronic hospital records were analysed to extract and abstract the information into data points. Please consider rephrasing.

Thank you. We have rephrased the beginning of the section so it more clearly specifies that it was a retrospective cohort study analysing patients’ electronic health records.

I find ‘Patients aged under 16 years were not included in the study’. Please specify (section ‘Results’) how many patients you have excluded’. If none, please delete this phrase. In addition, ‘patients aged under 16 years’. Is it a correct writing?

As you suggest, we have deleted this sentence. We have said the analysis was of adult patients in the first paragraph. No patients were excluded from the analysis.

Patients were identified by their International Classification of Diseases, 10th revision codes. This is unspecific writing. It remains unclear how this was done: by the authors or IT professionals. Also, ICD-10 codes could have been provided clearly (please do it). I am writing this because methods and data should be well-described so that they can be replicated and/or combined in different settings. That is a fundamental FAIR principle, https://www.go-fair.org/fair-principles/.

Thank you. The database was created by IT professionals from the local audit department and sent to the authors. What was assumed to be ICD-10 codes were, in fact, OPCS-4 procedure codes. We have now specified this in the second paragraph of the section with the codes they used to compile the list of patients. We apologise for this error.

The paragraph “Length of hospital stay referred to the number of post-operative days during the admission in which the operation took place. It did not include any prior admissions nor post-operative readmissions.” The second sentence is highly unusual. I would recommend deleting it.

We have deleted the paragraph.

Re “Estimated intra-operative blood loss was recorded by the operating surgeon in the operation note.” It is the most inaccurate and most diseased method of estimation of blood loss. It needs to be discussed in ‘Discussion’.

Thank you. We included this, as visual estimation is the most commonly used method of estimating and recording intraoperative blood loss. As you kindly suggest, we have added a paragraph highlighting its inaccuracy, and that our study reinforces that surgeons’ perceived blood loss does not correlate with risk of needing transfusion.

Re ‘post-operative haemoglobin was the lowest value within 30 days of the operation’. I don’t understand it (the lowest value). Please clarify.

Several patients had post-operative blood tests taken on multiple occasions. If this was the case, for the sake of our analysis, we defined “post-operative haemoglobin” as the lowest haemoglobin level. We have clarified this in the manuscript.

I find the phrase ‘All other data recorded in this study were complete.’ However, the Open Science Framework at https://osf.io/5uva4/ shows that this is not the case. Many empty cells within the Excel database (for example, cell H2, cell H29, Cell h44, etc.) indicate that not all data recordings in this study were completed. Please consider this point seriously and update the Open Science Framework accordingly (it is a pretty problematic task; you will need to communicate with the administrator of the Open Science Framework as a new dataset will generate a new DOI).

Thank you. We sincerely apologise for this inaccuracy. We have updated the manuscript under “Statistical analysis” to highlight the missing values in pre- and post-operative haemoglobin and body mass index, and explained how we have managed these in our analyses.

Statistical analysis. It would be useful to understand why the authors have shown the number of degrees of freedom in brackets. Please add the sentence and explain to the readers (including the patients and public) what that would mean – one degree of freedom or another. I say ‘the patients and public’ because the first subsection of Methods concerns the patients and public. For example, what does it mean (χ2 (3) = 90.3, p < 0.001)? I mean χ2 (3) = 90.3.

Thank you. After some deliberation, we have decided that showing the chi-squared values and degrees of freedom are complicating the readability of the manuscript without adding value to the messages we are trying to get across. We have therefore opted to exclude these and keep the p-values only.

I find that ‘Statistical analyses of categorical data were performed using Pearson’s chi-squared test. Also, I find the comparisons between 2 subgroups - n= 5 and n= 448. Please explain in the methods why you had chosen the chi-squared test instead of the exact Fisher’s test when one of the subgroups included only 5 patients. Would you consider conducting a new analysis with a more precise test in use?

Thank you. You are quite right that the Fisher’s exact test would have been more accurate for the analysis of categorical data. We have re-run the analyses for all those comparisons in which we had previously used Pearson’s chi-squared tests. We have updated the methodology and p-values in Table 1, in the body of the Results section and the Abstract accordingly. Those results that were previously statistically significant with Pearson’s chi-squared held as being statistically significant using Fisher’s; and those that did not reach statistically significance remained insignificant.

The area under the curve (AUC) can be used to visualise the sensitivity and specificity of a model predicting a certain outcome: the closer the AUC is to 1. That is correct; however, why do the authors use the verb form ‘can be’? The authors ‘used to visualise’ (not ‘can be used to visualise’). Please revise the paper from an academic language point of view.

Thank you. This sentence has been changed to “The area under the curve (AUC) represents the model's ability to distinguish between outcomes: the closer the AUC is to 1, the more accurately the model classifies the outcomes based on its sensitivity and specificity.”

Results

I find 28 patients with obstructive jaundice (1 + 27, Table 1). This has not been said in Methods. Please clarify.

These 28 patients comprised 19 patients who underwent elective cholecystectomy and 9 emergency “hot” operations. They all presented with obstructive jaundice and were investigated with MRCP and, if choledocholithiasis was confirmed, underwent removal of common bile duct stones with ERCP. Only after the CBD had been cleared did the patients undergo cholecystectomy. To clarify this, in the Methods section, we have added the following sentence: “Any patient who presented with obstructive jaundice was investigated with magnetic resonance cholangiopancreatography and, if required, underwent clearance of obstructing choledocholithiasis with endoscopic retrograde cholangiopancreatography prior to cholecystectomy.”

It is unusual to see no subtotal cholecystectomies in > 453 patients with such indications for surgery. Please provide a comment (Discussion). The source: Lunevicius R, et al., 2022 [Ref-1]

In our results, we did not divide the procedures into total and subtotal procedures; rather, we described the operative approach as laparoscopic, open or converted, anticipating that the size of incision and need to convert might contribute to the risk of blood loss and therefore need for transfusion. For clarity, we have relooked at the operation undertaken, and identified that 5 patients (1%) underwent subtotal procedures, all completed laparoscopically, and have added these to the “Operation type” heading in Table 1. We have added this as a new heading in the available data and reuploaded to the Open Science Framework, as well as adding a paragraph to the Results table. Patients who had a subtotal, rather than total, cholecystectomy were not more likely to receive a blood transfusion in our cohort. We have discussed these findings in the paragraph related to Nassar’s grading system and the association between operative difficulty increasing risk of bleeding.

Figure 1. Please specify Y-axis (Sensitivity)

Thank you. The y-axis label was inadvertently missed out. This has been reuploaded with the axis title.

The phrase ‘statistically significant is old-fashioned. Please speak about associations in your paper (you did it in Discussion – excellent writing)

Thank you for this advice. We have changed the phrasing when this occurred.

I find the ‘Supplementary Table’. This needs to be linked to the Supplementary Table source online.

Thank you. We have added the URL to our Open Science Framework project following mentions of the Supplementary Table. Here can be found both the Supplementary Table and our anonymised data.

Discussion

Please avoid writing this kind of ‘we are the first to demonstrate’. It doesn’t look good (especially in the context of your paper). Others will decide who is the first or the second (a higher Nassar scale grade is associated with a higher risk of bleeding)

Thank you, we have removed this on your advice.

Future prospective national studies with a larger sample size are required to further assess whether G&S routine testing is required and its associated safety. So, I am inclined to say that prospective national studies are unnecessary in light of references 1 – 14 and the results and findings of this study.

We have rephrased our concluding paragraph in the Discussion.

The point (rationale of the study) mentioned in the Introduction (“The authors have decided to conduct this study because the United Kingdom (UK) lacks national guidance recommending which patient or procedural factors warrant pre-operative G&S testing, although it has been shown, between 1999 and 2022, that G&S testing is overperformed before laparoscopic cholecystectomy in various health care facilities of the UK, and, therefore, a targeted approach should be adopted. The authors also emphasised that the decision to perform G&S testing relies on the clinical judgement of staff running pre-operative assessment clinics, i.e. on local resources and standard operative procedures) and requires discussion in light of the findings of this study.

Thank you, we have now brought our Discussion back round to the need for explicit national guidelines to help standardise G&S testing based on our findings and those of other studies.

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Competing Interests

We have no competing interests to declare.

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Reviewer Report

27 Views

10 Jun 2024 | for Version 1

Yulia Lin, University of Toronto, Toronto, ON, Canada

27 Views Cite this report Responses(1)

Approved With Reservations

Please clarify that this was a “retrospective” cross-sectional study.
Please clarify whether transfusion data were obtained from the electronic record linked to the transfusion laboratory information system as chart records that are not linked can be inaccurate.
This is a comment for the authors’ institution. Many institutions allow a group and save to be done within 30 days of the procedure (rather than only 5 days) provided that the patient has not received a transfusion or been pregnant in the 3 months prior. This may increase efficiency for patients who do require a G&S.

Results

Please clarify the hospital policy for type of blood for emergency uncrossmatched blood. Most institutions would provide group O positive blood and only group O negative to individuals of childbearing potential. Depending on the hospital policy, the text should be revised to group O uncrossmatched blood. This change is suggested to avoid the common misconception that only group O negative can be given in an emergency uncrossmatched scenario. (This also applies to the reference to group O negative in the Discussion).
Please clarify if the cost of the preoperative G&S tests includes only the ASA grade I and II patients or all G&S done preoperatively for this cohort.
In the logistic regression, the only independent factor that was associated with perioperative blood transfusion was prior emergency hospital attendance. It should be stated that the association of higher ASA and hematological malignancy was only seen in univariable analysis in the Abstract.

Discussion

The primary question of the study was the frequency of G&S testing and perioperative blood transfusion as noted in the first sentence of the conclusion. Suggest that paragraph 6 of the Discussion be the first paragraph summarizing the main findings of the study.
While the association of previous emergency attendance was noted in this study, the sample size of events (patients who received a blood transfusion) is only 5. Any statistical associations found (or not found) are limited given that there are so few events. Please add this major limitation.

Conclusion

Because patients who has prior emergency attendance had greater risk of blood transfusion, does not necessarily translate to those patients requiring surgery on their emergency attendance. Suggest de-emphasizing this inference. (This also applies to the final paragraph in the Plain English summary)
It would be reasonable to suggest potential criteria for G&S e.g. prior emergency hospital attendance, higher ASA and known history of haematological malignancy.

Is the work clearly and accurately presented and does it cite the current literature?

Yes
Is the study design appropriate and is the work technically sound?

Yes
Are sufficient details of methods and analysis provided to allow replication by others?

Yes
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Partly

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Transfusion Medicine clinical practice, education and quality improvement

Respond to this report

Responses (1)

Author Response

23 Oct 2024

Lawrence O'Leary, Department of General Surgery, West Middlesex University Hospital, London, TW7 6AF, UK

Dear Dr Lin,
We really appreciate you taking the time to review our article and thank you for your expertise and advice on how we can make our messages clearer. We have responded to each of your suggested clarifications in turn below.

Yours sincerely,
Mr Lawrence O’Leary, on behalf of the authors

1. Reviewer: Methods - Please clarify that this was a “retrospective” cross-sectional study.
Author Response: Thank you – we have added this important detail to both the main manuscript Methods section and the abstract.

2. Reviewer: Please clarify whether transfusion data were obtained from the electronic record linked to the transfusion laboratory information system as chart records that are not linked can be inaccurate.
Author Response: In our institution, the patient electronic records are automatically updated with product type and volume by the transfusion laboratory when blood products are released to the wards. We primarily used this information to identify when blood products were prescribed, and confirmed these were administered by cross-referencing patient fluid balance charts. We have clarified this in the Methods section as you kindly suggest.

3. Reviewer: This is a comment for the authors’ institution. Many institutions allow a group and save to be done within 30 days of the procedure (rather than only 5 days) provided that the patient has not received a transfusion or been pregnant in the 3 months prior. This may increase efficiency for patients who do require a G&S.
Author Response: Thank you for this comment. We have checked with our transfusion laboratory, and confirmed they allow group and saves within 30 days of the procedure provided the same criteria you list are met. We have fed this back to our department.

4. Reviewer: Results - Please clarify the hospital policy for type of blood for emergency uncross matched blood. Most institutions would provide group O positive blood and only group O negative to individuals of childbearing potential. Depending on the hospital policy, the text should be revised to group O uncross matched blood. This change is suggested to avoid the common misconception that only group O negative can be given in an emergency uncross matched scenario. (This also applies to the reference to group O negative in the Discussion).
Author Response: We have confirmed this is the case in our unit and as per our national British Society for Haematology guidelines and corrected the manuscript accordingly.

5. Reviewer: Please clarify if the cost of the preoperative G&S tests includes only the ASA grade I and II patients or all G&S done preoperatively for this cohort.
Author Response: The costing was for the whole cohort, and we have amended this to make this clearer.

6. Reviewer: In the logistic regression, the only independent factor that was associated with perioperative blood transfusion was prior emergency hospital attendance. It should be stated that the association of higher ASA and hematological malignancy was only seen in univariable analysis in the Abstract.
Author Response: Thank you – this has been clarified in the Abstract.

7. Reviewer: Discussion - The primary question of the study was the frequency of G&S testing and perioperative blood transfusion as noted in the first sentence of the conclusion. Suggest that paragraph 6 of the Discussion be the first paragraph summarizing the main findings of the study.
Author Response: We agree with this suggestion, and have rearranged the Discussion section as per your advice.

8. Reviewer: While the association of previous emergency attendance was noted in this study, the sample size of events (patients who received a blood transfusion) is only 5. Any statistical associations found (or not found) are limited given that there are so few events. Please add this major limitation.
Author Response: Thank you – we have made the Limitations paragraph clearer to reflect this.

9. Reviewer: Conclusion - Because patients who has prior emergency attendance had greater risk of blood transfusion, does not necessarily translate to those patients requiring surgery on their emergency attendance. Suggest de-emphasizing this inference. (This also applies to the final paragraph in the Plain English summary)
Author Response: Our intention was not to infer that these patients should necessarily have a “hot” emergency cholecystectomy; rather, that these elective operations should be treated as urgent, and delays to operations avoided. We have therefore clarified this in the Plain English summary and Conclusion by adding that delays to planned operations should be avoided.

10. Reviewer: It would be reasonable to suggest potential criteria for G&S e.g. prior emergency hospital attendance, higher ASA and known history of haematological malignancy.
Author Response: Thank you, we have added this suggestion.

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Competing Interests

We have no competing interests to declare.

Alongside their report, reviewers assign a status to the article:

Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested

Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.

Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions

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Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study

Abstract

Background

Methods

Results

Conclusions

Plain Language Summary

Plain english summary

Keywords

Revised Amendments from Version 1

Introduction

Methods

Patient and public involvement

Study methodology

Statistical analysis

Statement of ethics

Results

Table 1. Patient demographics stratified by whether they received a blood transfusion.

Figure 1. Receiver Operating Characteristic (ROC) curve analysis of number of prior emergency hospital attendances and its impact on the requirement for post-operative blood transfusion.

Discussion

Conclusions

Data availability

Underlying data

References

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Open Peer Review

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Open Peer Review

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Reviewer Reports

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Are you an NIHR-funded researcher?

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Assessment of routine pre-operative group and save testing in patients undergoing cholecystectomy: a retrospective cohort study

Abstract

Background

Methods

Results

Conclusions

Plain Language Summary

Plain english summary

Keywords

Revised Amendments from Version 1

Introduction

Methods

Patient and public involvement

Study methodology

Statistical analysis

Statement of ethics

Results

Table 1. Patient demographics stratified by whether they received a blood transfusion.

Figure 1. Receiver Operating Characteristic (ROC) curve analysis of number of prior emergency hospital attendances and its impact on the requirement for post-operative blood transfusion.

Discussion

Conclusions

Data availability

Underlying data

References

Comments on this article Comments (0)

Open Peer Review

Comments on this article Comments (0)

Open Peer Review

Reviewer Status

Reviewer Reports

Comments on this article

Competing Interests Policy

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Are you an NIHR-funded researcher?

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