Objective Whether sex-related differences in the prognosis of infective endocarditis (IE) are due to differences in disease severity or comorbid patterns, physiological specificities or a treatment indication bias is unclear. We conducted an analysis of the pooled database of two population-based cohorts of IE to reassess the relationships between sex, early valve surgery (EVS) and outcome in patients with IE.

Methods Demographic and baseline characteristics, complications and outcome were compared in men and women with Duke-definite left-sided IE. A propensity model for EVS was constructed using multivariate logistic regression. Factors associated with 1-year mortality were identified using multivariate Cox models adjusted for EVS factors.

Results The study population included 466 (75%) men and 154 (25%) women. Compared with men, women were older (p=0.005), were more often on haemodialysis (p=0.04), more often had a mitral valve IE (50.0% vs 35.8%, p=0.02), less often developed a septic shock (p=0.05), less often underwent EVS (p=0.001) yet had comparable inhospital mortality rates (20.1% vs 20.0%, p=0.96) and similar 1-year survival probability (logrank p=0.68). Female sex was neither associated with EVS (OR 0.76 (95% CI 0.49 to 1.16)) nor mortality (HR 1.17 (95% CI 0.80 to 1.69)). However EVS was associated with an increased risk of death in women in the early postoperative period (HR 8.72 (95% CI 3.42 to 22.24), p=<0.0001).

Conclusions Women underwent EVS less often than men. However female sex was independently associated with neither EVS nor 1-year mortality. The reasons for a higher risk of early postoperative mortality in women must still be elucidated.