ObjectiveTo investigate the association between female sex and 30-day mortality and postoperative complications in patients undergoing scheduled proximal thoracic aortic surgery in Sweden. MethodsIn a nationwide population-based cohort study, all patients who underwent scheduled proximal thoracic aortic surgery in Sweden between 2016 and 2020 were included. The primary outcome measure was 30-day mortality. Secondary outcome measure included a combined endpoint including 30-day all-cause mortality, postoperative new onset dialysis, perioperative stroke or a prolonged need of postoperative ventilation (>48 hours). Logistic regression models and propensity score matching were used to estimate the association between female sex and primary and secondary outcomes adjusted for differences in baseline characteristics. Results2000 patients (29% women) were analyzed. The crude 30-day all-cause mortality rate was higher in women compared to men (3.1 vs. 1.4%, p<0.001). Women were older at time of surgery (65.6 vs. 60.2 years, p<0.001), had more comorbidities and a larger maximum indexed aortic diameter (cm/m body height) at time of surgery (3.4 ± 0.56 vs. 3.0 ± 0.48, p<0.001). The adjusted risk for 30-day mortality for women compared to men was not significant (OR 1.41 CI 95% (0.70-2.83)), neither was the secondary composite endpoint (OR 0.89 CI 95% (0.62-1.27)). The propensity score matched analysis showed similar results. ConclusionsWomen who underwent proximal thoracic aortic surgery had a two-fold higher unadjusted 30-day mortality risk, but the mortality risk was not significantly higher when age and comorbidities was taken into consideration.