Association between anaesthetist hepatopancreatobiliary volume and outcomes

Volume–outcome relationships in hepato-pancreatobiliary (HPB) surgery are well established for surgeons and hospitals1. Volume–outcome also applies to anaesthesiologists; care by anaesthesiologists performing ≥6 HPB cases annually is associated with reduced major morbidity rate2. Hospitals with more patients receiving high-volume anaesthesiology care are also associated with lower major morbidity rate3. Specialized anaesthesiology teams present an opportunity to improve outcomes4. However, establishing high-volume specialized HPB anaesthesiology teams presents challenges5. Anaesthesiologists have concerns about losing experience and expertise in non-HPB cases, which they worry could compromise outcomes. To inform HPB anaesthesiology models of care, we examined the association between anaesthesiologist HPB and non-HPB surgery volumes. We conducted a population-based retrospective cohort study in Ontario, Canada (Table S1). Anaesthesiologists who performed hepatectomy and pancreatectomy in adults ≥ 18 years old over 2009–2023 were identified. The outcome was anaesthesiologist’s non-HPB surgery volume, computed as the non-HPB surgeries volume per calendar year (Table S2). The exposure was the anaesthesiologist’s HPB surgery volume, captured as the number of HPB surgeries performed for each calendar year. The relationship between exposure and outcome was represented with line graphs. Negative binomial regression fitted by generalized estimating equations examined the association between exposure and outcome at the anaesthesiologist level, adjusted for anaesthesiologist age, sex, years in practice, and hospital status. We first assessed the association in absolute numbers of surgeries, and second with an offset of total number of days worked by an anaesthesiologist in each year. Supplementary material provides methodology details.