Protocol for a multicentre, prospective, population-based cohort study of variation in practice of cholecystectomy and surgical outcomes (The CholeS study).

INTRODUCTION: Cholecystectomy is one of the most common general surgical operations performed. Despite level one evidence supporting the role of cholecystectomy in the management of specific gallbladder diseases, practice varies between surgeons and hospitals. It is unknown whether these variations account for the differences in surgical outcomes seen in population-level retrospective data sets. This study aims to investigate surgical outcomes following acute, elective and delayed cholecystectomies in a multicentre, contemporary, prospective, population-based cohort.

METHODS AND ANALYSIS: UK and Irish hospitals performing cholecystectomies will be recruited utilising trainee-led research collaboratives. Two months of consecutive, adult patient data will be included. The primary outcome measure of all-cause 30-day readmission rate will be used in this study. Thirty-day complication rates, bile leak rate, common bile duct injury, conversion to open surgery, duration of surgery and length of stay will be measured as secondary outcomes. Prospective data on over 8000 procedures is anticipated. Individual hospitals will be surveyed to determine local policies and service provision. Variations in outcomes will be investigated using regression modelling to adjust for confounders.

ETHICS AND DISSEMINATION: Research ethics approval is not required for this study and has been confirmed by the online National Research Ethics Service (NRES) decision tool. This novel study will investigate how hospital-level surgical provision can affect patient outcomes, using a cross-sectional methodology. The results are essential to inform commissioning groups and implement changes within the National Health Service (NHS). Dissemination of the study protocol is primarily through the trainee-led research collaboratives and the Association of Upper Gastrointestinal Surgeons (AUGIS). Individual centres will have access to their own results and the collective results of the study will be published in peer-reviewed journals and presented at relevant surgical conferences.