Objectives: Age and sex-specific differences exist in acute myocardial infarction (AMI) prevalence, morbidity and mortality. Thus, within a diverse integrated health care delivery system of over 4 million members, we examined how sex-specific temporal trends in AMI incidence may have contributed to these differences and reflect evolving changes in AMI prevention efforts.
Methods: We identified all Kaiser Permanente Southern California members (aged ≥35 years) with a primary ICD-9-CM hospital discharge diagnosis of AMI between January 1, 2000 and December 31, 2014. Incident AMI hospitalization was defined as the first event documented in the electronic health record between 2000 and 2014, with no prior AMI hospitalization. Incident ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) were identified similarly. Age-standardized (using U.S. 2010 Census data) and age-specific incidence rates by sex were calculated separately for AMI, STEMI and NSTEMI events for each calendar year. Average annual percent change and 95% confidence intervals (CIs) were estimated using log-linear Poisson models.
Results: A total of 45,331 AMI, 16,524 STEMI and 32,552 NSTEMI incident events were identified between 2000 and 2014. Age-standardized incidence rates (per 100,000 person years) of AMI declined an average of 4.7%/year (95% CI [4.4, 4.9]) for men from 441.9 in 2000 to 223.6 in 2014 and 3.9%/year (95% CI [3.6, 4.2]) for women from 246.5 in 2000 to 146.4 in 2014. NSTEMIs declined an average of 2.8%/year (95% CI [2.5, 3.2]) for men from 268.2 in 2000 to 170.2 in 2014 and 1.9%/year (95% CI [1.5, 2.3]) for women from 156.1 in 2000 to 121.8 in 2014. Although STEMI incidence rates declined substantially from 2000 to 2014, sex differences were minimal, with an average decline of 8.0%/year (95% CI [7.6, 8.4]) for men from 205.9 in 2000 to 67.5 in 2014 and 8.9%/year (95% CI [8.3, 9.5]) for women from 107.2 in 2000 to 32.3 in 2014. Comparing 2000 to 2014, age-specific incidence rates of AMI, NSTEMI and STEMI declined in both men and women across all age groups (Table).
Conclusions: Despite absolute differences, both men and women have experienced similar declines in hospitalized AMI, STEMI and NSTEMI incidence rates, presumably due to increased efforts in both primary and secondary AMI prevention.