The relationship of hospital and surgeon volume indicators and post-operative outcomes in pancreatic surgery: a systematic literature review, meta-analysis and guidance for valid outcome assessment

Background: Available evidence on the volume-outcome relationship after pancreatic surgery is limited due to the narrow focus of interventions, volume indicators and outcomes considered as well as due to methodological differences of the included studies. Therefore, we aim to evaluate the volume-outcome relationship following pancreatic surgery following strict study selection and quality criteria, to identify aspects of methodological variation and to define a set of key methodological indicators to consider when aiming for comparable and valid outcome assessment.Methods: Four electronic databases were searched to identify studies on the volume-outcome rela-tionship in pancreatic surgery published between the years 2000-2018. Following a double-screening process, data extraction, quality appraisal, and subgroup analysis, results of included studies were stratified and pooled using random effects meta-analysis.Results: Consistent associations were found between high hospital volume and both postoperative mortality (OR 0.35, 95% CI: 0.29-0.44) and major complications (OR 0.87, 95% CI: 0.80-0.94). A sig-nificant decrease in the odds ratio was also found for high surgeon volume and postoperative mortality (OR 0.29, 95%CI: 0.22-0.37). Discussion: Our meta-analysis confirms a positive effect for both hospital and surgeon volume in-dicators for pancreatic surgery. Further harmonization (e.g. surgery types, volume cut-offs/definition, case-mix adjustment, reported outcomes) are recommended for future empirical studies.