Objective: To investigate the association between surgeon-anesthesiologist sex discordance and patient mortality after noncardiac surgery.

Background: Evidence suggests different practice patterns exist among female and male physicians. However, the influence of physician sex on team-based practices in the operating room and subsequent patient outcomes remains unclear in the context of noncardiac surgery.

Methods: We conducted a population-based, retrospective cohort study of adult Ontario residents who underwent index, inpatient noncardiac surgery between January 2007 and December 2017. The primary exposure was physician sex discordance (ie, the surgeon and anesthesiologist were of the opposite sex). The primary outcome was 1-year mortality. The association between physician sex discordance and patient outcomes was modeled using multivariable Cox proportional hazard regression with adjustment for relevant physician, patient, and hospital characteristics.

Results: Of 541,209 patients, 158,084 (29.2%) were treated by sex-discordant physician teams. Physician sex discordance was associated with a lower rate of mortality at 1 year [5.2% vs. 5.7%; adjusted HR: 0.95 (0.91-0.99)]. Patients treated by teams composed of female surgeons and male anesthesiologists were more likely to be alive at 1 year than those treated by all-male physician teams [adjusted HR: 0.90 (0.81-0.99)].

Conclusions: Noncardiac surgery patients had a lower likelihood of 1-year mortality when treated by sex-discordant surgeon-anesthesiologist teams. The likelihood of mortality was further reduced if the surgeon was female. Further research is needed to explore the underlying mechanisms of these observations and design strategies to diversify operating room teams to optimize performance and patient outcomes.