Surgery for acute cholecystitis in severely comorbid patients: a population-based study on acute cholecystitis | BMC Gastroenterology

The Swedish Ethical Review Authority approved the study, dnr 2021–00,862. The manuscript was prepared using the RECORD guidelines. [17]

Data collection

Data for all patients with a diagnosis of acute cholecystitis and cholecystitis with and without gallstones (ICD K80.0, K80.1, K81.0-K801.9) between 2017 and 2020 was requested from the administrative data offices of Region Gävleborg and Region Uppsala. Electronic patient records (EPR) were then screened, and data was recorded by five of the authors after an introduction to the tools and variables. Patients with acute cholecystitis based on Tokyo guidelines diagnostic criteria and no other diagnosis explaining the symptoms, e.g. cholangitis or pancreatitis were included in the study. [18]

Study data were collected and managed using REDCap electronic data capture tools hosted at Uppsala University [19, 20]. Additional data for patients who had a cholecystectomy was then requested from Gallriks using personal identification numbers to supplement the EPR data [15]. For the final data set, missing ASA classification from EPR was supplemented from Gallriks and faulty dates were checked against the EPR and Gallriks and corrected.

Patients were stratified according to the treatment choice at index cholecystitis (surgery or NOM, including cholecystostomy).


The primary outcome for patients treated with surgery was peri- and postoperative complications which were classified as: no complication, complications treated without general anaesthesia (Clavien-Dindo ≤ 3a), and complications requiring new surgery, leading to organ failure, ICU care or death (Clavien-Dindo ≥ 3b). [21]

For NOM patients the primary outcome was second gallstone complication or index cholecystitis treatment failure, i.e. recurrence, and the date of complication or diagnosis of treatment failure.

Data on second gallstone complications and handling of the gallbladder (surgery or NOM)

was collected from the EPR with follow-up set to the date of EPR review for time-to-event analysis. Date of death or follow-up without death was collected from EPR for all patients and from Gallriks for patients who had surgery. Time to second gallstone complication was defined as the time from diagnosis to new gallstone disease with censoring for follow-up and death. The secondary outcome, length of stay, was collected from the EPR.

The exposure, ASA classification, was determined from EPR with reference to examples translated to Swedish. [2, 22]

Sex, age, smoking, BMI, CCI and separate comorbidities, cholecystitis grade and time from symptoms to surgery were included as potential confounders. Comorbidities were recorded as cardiovascular disease (heart disease, peripheral vascular and cerebrovascular disease), diabetes, pulmonary disease (COPD, asthma, or other chronic pulmonary diseases), other diseases (grouped due to the small number of cases, dementia, kidney failure, liver failure, tumours) and increased bleeding risk (anticoagulant use or hereditary bleeding disorders) using data from EPR and Gallriks. The cholecystitis grade was classified as Grade 1 or grade 2–3 since complete data on organ and systemic dysfunction was not readily available in the electronic patient records, patients without grade II features were assumed to not have organ dysfunction. [18]


Patients were stratified by index treatment: surgery or NOM, and ASA classification to analyse outcomes and demographics. Differences between groups were tested with the Chi-Square test for categorical variables and Mann–Whitney U and Kruskal–Wallis test for discrete variables to avoid normality assumptions.

Gallriks data was compared with the data recorded in the database regarding complications with the Cohen’s kappa coefficient and Pearson’s correlation coefficient for continuous data.

Logistic regressions were used to investigate the risk of complications. Sex, age, smoking, BMI, CCI, diabetes, cardiovascular disease, pulmonary disease, other comorbidities, grade of cholecystitis, and time to surgery were analysed individually to investigate the correlation with postoperative outcomes. The adjusted analysis excluded the individual comorbidities since these are included in ASA and CCI measurements.

The risk of readmission and 30-day mortality and the length of stay for ASA3 patients treated with and without surgery was investigated with propensity score matching. Patients were matched on age, sex, CCI, BMI, grade of cholecystitis, centre, and time from symptoms to admission. The MatchIt R-package was used, with the method “nearest”, caliper of 0.1 and a generalised linear model to assess the distance [23]. Differences in mortality and readmission were tested with logistic regression and length of stay was tested with linear regression. Standard errors were calculated using a cluster robust method.

Sensitivity analysis on the proportion of complications in different ASA classifications was performed using data from Gallriks.

Cox regression was used to investigate time to second gallstone complication in NOM patients, censoring was used.

Statistics were calculated with R version 3.14 (Vienna, Austria). Cases with missing data were included for analysis in differences between groups and reported in tables while they were removed in regression analysis. P-values of < 0.05 were considered statistically significant, analysis was exploratory without correction for multiple testing.

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