Statistical models to preoperatively predict operative difficulty in laparoscopic cholecystectomy: a systematic review

Background: Laparoscopic cholecystectomy operative difficulty is highly variable and influences outcomes. This systematic review analyzes the performance and clinical value of statistical models to preoperatively predict laparoscopic cholecystectomy operative difficulty. Methods: PRISMA guidelines were followed. PubMed, Embase, and the Cochrane Library were searched until June 2020. Primary studies developing or validating preoperative models predicting laparoscopic cholecystectomy operative difficulty in cohorts of >100 patients were included. Studies not reporting performance metrics or enough information for clinical implementation were excluded. Data were extracted according to CHARMS, and study quality was assessed using the PROBAST tool. Results: In total, 2,654 articles were identified, and 22 met eligibility criteria. Eighteen were model development, whereas 4 were validation studies. Eighteen studies were at high risk of bias. However, 11 studies showed low concern for applicability. Identified models predict 9 definitions of laparoscopic cholecystectomy operative difficulty, the most common being conversion to open surgery and operating time. The most validated models predict an intraoperative difficulty scale and procedures >90 minutes with an area under the curve of >0.70 and >0.76, respectively. Commonly used predictors include demographic variables such as age and gender (9/18 models) and ultrasound findings such as gallbladder wall thickness (11/18). Clinical implementation was never studied. Conclusion: There is a longstanding interest in estimating laparoscopic cholecystectomy operative difficulty. Models to preoperatively predict laparoscopic cholecystectomy operative difficulty have generally good performance and seem applicable. However, an unambiguous definition of operative difficulty, validations, and clinical studies are needed to implement patients’ stratification in laparoscopic cholecystectomy.