Uncovering variation in cholecystitis treatment: protocol and statistical analysis plan for a nationwide observational study - the Dutch Cholecystitis Snapshot Study (Dutch CHESS).

INTRODUCTION: Cholecystitis is a highly prevalent disease that imposes a substantial burden on the healthcare system. Despite strong underlying evidence, guideline adherence in the treatment of cholecystitis remains low. Moreover, important gaps in knowledge persist that must be addressed to optimise existing guidelines. The primary aim is to assess the nationwide variation in cholecystitis treatment and identify opportunities to improve guideline adherence. Secondary aims include determining the best cystic duct closure method; the best model to predict concomitant choledocholithiasis; the optimal treatment for cholecystitis lasting 7 days or more at diagnosis and the optimal strategy for gallbladder drainage and post-drainage care.

METHODS AND ANALYSIS: The Dutch CHESS is a multicentre observational cohort study, including 67 out of 69 Dutch hospitals. From 1 April to 30 September 2024, all patients diagnosed with cholecystitis (Tokyo Guidelines definition) will be prospectively identified. Data on patient characteristics, treatment and outcome (with 6-month follow-up) will be collected to address the primary and secondary aims. For the primary aim, guideline adherence is defined as the percentage of patients who undergo early cholecystectomy for cholecystitis lasting 0-7 days. Current adherence, nationally and for each individual hospital, along with predictors of adherence, will be determined. The adherence of each hospital will be set against the national average and best practices. To further support improvement, the impact of guideline adherence on total hospital stay and morbidity will be determined. Three months after performance feedback to the participating hospitals, the impact on local practice will be assessed through questionnaires. Subgroup analyses and statistical methods for addressing both the primary and secondary aims are predefined in this protocol.

ETHICS AND DISSEMINATION: The Medical research Ethics Committees United reviewed the protocol and decided that the Dutch Medical Research Involving Human Subjects Act is not applicable (reference Number: W23.225). Approval was obtained from the institutional review board and board of directors at each participating hospital. Results will be disseminated through peer-reviewed publications and conference presentations.

STUDY REGISTRATION NUMBER: ClinicalTrials.gov, NCT06349863; Pre-results.