National gender-specific trends in myocardial infarction hospitalization rates among patients aged 35 to 64 years.

In recent years, the prevalence of myocardial infarction (MI) has increased among women and decreased among men aged 35 to 54 years. To determine the extent to which changes in incidence account for recent variations in prevalence, we assessed the temporal trends in gender-specific hospitalization rates for MI. Using the Nationwide Inpatient Sample, we identified patients aged 35 to 64 years admitted to United States hospitals with a primary discharge diagnosis of MI from 1997 to 2006 (n = 2,824,615). The age-standardized MI hospitalization rates per 100,000 subjects were assessed for men and women aged 35 to 44, 45 to 54, and 55 to 64 years. The MI hospitalization rates per 100,000 subjects decreased by 26% from 168 to 126 for men and by 18% from 56 to 46 for women (both p <0.001). The reductions in the MI hospitalization rates were greatest among men aged 45 to 54, men aged 55 to 64, and women aged 55 to 64 years (standardized rates of change -3%, -4%, and -3% annually, p <0.001). The MI hospitalization rates decreased slightly for women aged 45 to 54 years and men aged 35 to 44 years (standardized rate of change -2% annually, p <0.001) and increased for women aged 35 to 44 years (standardized rate of change 2% annually, p = 0.008). In conclusion, from 1997 to 2006, men and women aged 35 to 64 years experienced an overall decrease in MI hospitalization rates; the reductions were more pronounced in men than in women. The slight increase in MI hospitalizations among women aged 35 to 44 years might have played a small role in the previously noted increases in MI prevalence among middle-age women.