Sex differences in 2-year mortality after hospital discharge for myocardial infarction

Background: An interaction between sex and age is thought to affect hospital mortality after myocardial infarction; younger, but not older, women have been shown to have higher mortality rates than men. It is currently unknown whether findings are similar after hospital discharge. Objective: To determine whether an interaction between sex and age affects a-year mortality after myocardial infarction. Design: Community-based prospective cohort study. Setting: 16 community hospitals serving the Worcester, Massachusetts, metropolitan area. Patients: 6826 patients who survived hospitalization for acute myocardial infarction during ten 1-year periods between 1975 and 1995. Measurements: Mortality 2 years after hospital discharge. Results: The overall 2-year mortality rate was higher in women (28.9%) than in men (19.6%). When patients were examined by age group, however, only women younger than 60 years of age had a higher mortality rate than men of similar age. The sex difference decreased with increasing age; among the oldest patients, women had a lower mortality rate than men (P = 0.009 for the interaction between sex and age). This relationship was not affected by adjustment for demographic characteristics and medical history, clinical characteristics, and hospital and discharge treatments; the hazard of 2-year death for women compared with men increased 15.4% (95% Cl, 4.3% to 27.6%) for every 10-year decrease in age. In absolute terms, after adjustment for demographic characteristics and medical history, among patients younger than 60 years of age women were at greater risk than men (risk difference, 1.8 percentage points). At older ages, however, women were at lower risk than men. Conclusions: Younger, but not older, women who survive hospitalization for myocardial infarction have a higher long-term mortality rate than men. This provides additional evidence that younger women with myocardial infarction are at greater risk for death than men.