Association Between Anesthesiologist Sex and Patients' Postoperative Outcomes: A Population-based Cohort Study

Objective: To examine the association of anesthesiologist sex on postoperative outcomes. Background: Differences in patient postoperative outcomes exist, depending on whether the primary surgeon is male or female, with better outcomes seen among patients treated by female surgeons. Whether the intraoperative anesthesiologist's sex is associated with differential postoperative patient outcomes is unknown. Methods: We performed a population-based, retrospective cohort study among adult patients undergoing one of 25 common elective or emergent surgical procedures from 2007 to 2019 in Ontario, Canada. We assessed the association between the sex of the intraoperative anesthesiologist and the primary end point of the adverse postoperative outcome, defined as death, readmission, or complication within 30 days after surgery, using generalized estimating equations. Results: Among 1,165,711 patients treated by 3006 surgeons and 1477 anesthesiologists, 311,822 (26.7%) received care from a female anesthesiologist and 853,889 (73.3%) from a male anesthesiologist. Overall, 10.8% of patients experienced one or more adverse postoperative outcomes, of whom 1.1% died. Multivariable adjusted rates of the composite primary end point were higher among patients treated by male anesthesiologists (10.6%) compared with female anesthesiologists (10.4%; adjusted odds ratio 1.02, 95% CI: 1.00-1.05, P=0.048). Conclusions: We demonstrated a significant association between sex of the intraoperative anesthesiologist and patient short-term outcomes after surgery in a large cohort study. This study supports the growing literature of improved patient outcomes among female practitioners. The underlying mechanisms of why outcomes differ between male and female physicians remain elusive and require further in-depth study.