Sex differences in survival after myocardial infarction in Sweden. Data from the Swedish National Acute Myocardial Infarction register

AIMS: Women, particularly younger women, hospitalized with acute myocardial infarction have been found to have poorer prognosis than men. A large proportion of deaths due to myocardial infarction, however, occur in the pre-hospital phase. We set out to analyse age-specific sex differences in survival after myocardial infarction at different time intervals from the onset of acute myocardial infarction, including pre-hospital deaths and 1-year overall survival. METHODS AND RESULTS: The National Acute Myocardial Infarction Register in Sweden was used to analyse age-specific sex differences in mortality outside hospital, 28-day mortality and 1-year mortality in 353 905 cases occurring between 1987 and 1995 in Swedish men and women aged 30 to 89 years. Overall, one in four of all myocardial infarction victims died outside hospital. At all ages, except in individuals younger than 50 years, men had higher pre-hospital mortality. The odds of dying within 28 days for women below 50 years of age, compared to men, was 1.84 (1.56--2.18) in hospitalized patients and 1.31 (1.18--1.46) in all infarction patients. Above the age of 65, in the total population with myocardial infarction, women had a better prognosis, with odds ratios ranging from 0.83 to 0.89. In patients surviving the first 28 days, 4.0% of the women and 2.9% of the men below the age of 50 were dead within a year after the infarction, odds ratio 1.37 (1.06--1.76). This excess mortality was mainly due to diabetes and non-cardiac causes. Only women younger than 50 years had a significantly poorer overall 1-year survival than men of the same age. At the age of 70 or more, women had a small survival advantage. CONCLUSION: In the total acute myocardial infarction population, only women under 50 years of age have a consistently worse prognosis than men. Much of the excess mortality in young women seems to be associated with diabetes.