Sex differences in the prognosis of congestive heart failure : Results from the Cardiac Insufficiency Bisoprolol Study (CIBIS II)

Whether female sex is associated with a better prognosis in patients with congestive heart failure (CHF) remains uncertain. The Cardiac Insufficiency Bisoprolol Study (CIBIS) II showed that bisoprolol reduced all-cause mortality and morbidity rates in CHF patients treated with diuretics and ACE inhibitors. We examined whether survival was different in men (n=2132) and women (n=515) enrolled in CIBIS II. Women differed from men with regard to age, NYHA functional classification, primary cause of CHF, and risk factors such as left bundle-branch block. After adjustment for baseline differences, the probability of all-cause mortality was significantly reduced by 36% in women compared with that in men (hazard ratio 0.64, 95% CI 0.47 to 0.86, P:=0.003). Women also had a 39% reduction in cardiovascular deaths (hazard ratio 0.64, 95% CI 0.45 to 0.91, P:=0.01) and a 70% reduction in deaths from pump failure (hazard ratio 0.30, 95% CI 0.13 to 0.70, P:=0.005) compared with men. Kaplan-Meier survival analysis revealed a significant reduction in all-cause mortality among women treated with bisoprolol compared with men (6% versus 12% P:=0.01) but not among women treated with placebo (13% versus 18%, P:=0.10). However, this sex/ss-blocker effect was not significant in multivariate analysis. These results indicate that regardless of ss-blocker treatment and baseline clinical profile, female sex is a significant independent predictor of survival in patients with CHF.