Sex differences in the effectiveness of statins after myocardial infarction

BACKGROUND: We sought to investigate the sex differences in the effectiveness of statins in patients with acute myocardial infarction (AMI). METHODS: Linking hospital discharge and drug claims databases from Quebec, Canada (1998-2004), we identified statin users (n = 14 710) and non-users (n = 23 833) discharged from hospital after an AMI-related hospital stay and followed up for as long as 7 years. RESULTS: All-cause death rates were 4.1 and 14.6 per 100 person-years among users and non-users, respectively, whereas cardiac death rates were 2.2 and 7.4 per 100 person-years. For death from any cause, the adjusted hazard ratios associated with statin use in women were 0.61 (95% confidence interval [CI], 0.54-0.69) within 1 year of follow-up, 0.55 (0.48-0.63) at 1-3 years and 0.38 (0.31-0.49) at > 3 years; in men, the corresponding estimates were 0.54 (0.48-0.60), 0.48 (0.42-0.55) and 0.34 (0.30-0.39). For cardiac-related death, the adjusted hazard ratios associated with statin use in women were 0.70 (0.60-0.81) within 1 year, 0.56 (0.46-0.68) at 1-3 years and 0.44 (0.31-0.62) at > 3 years of follow-up, whereas in men, the estimates were 0.59 (0.51-0.69), 0.47 (0.39-0.58) and 0.37 (0.30-0.45), respectively. INTERPRETATION: Statin therapy after an AMI was associated with reduced rates of all-cause and cardiac mortality. The effect increased with time in both sexes, but the degree of risk reduction was less for women than for men.