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 followup, 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.