Trends in and disparities for acute myocardial infarction: an analysis of Medicare claims data from 1992 to 2010

Background: It is unknown whether previously reported disparities for acute myocardial infarction (AMI) by race and sex have declined over time. Methods: We used Medicare Part A administrative data files for 1992 to 2010 to evaluate changes in per-capita hospitalization rates for AMI, rates of revascularization (percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG)), and 30-day mortality for four distinct patient subcohorts: black women; black men; white women; and white men, adjusted for age, comorbidities and year using logistic regression. Results: The study sample consisted of 4,045,267 AMI admissions between the years 1992 and 2010 (166,660 black women; 116,201 black men; 1,870,816 white women; 1,891,590 white men). AMI hospitalization rates differed significantly in 1992 to 1993 among black women (61.6 hospitalizations per 10,000 Medicare enrollees), black men (73.2 hospitalizations), white women (72.0 hospitalizations) and white men (113.2 hospitalizations) (P < 0.0001). By 2009 to 2010 AMI hospitalization rates had declined substantially in all cohorts but disparities remained with significantly lower hospitalization rates among women and blacks compared to men and whites, respectively (P < 0.0001). In multivariable-adjusted analyses, despite narrowing of the differences between cohorts over time, disparities in AMI hospitalization rates by race and sex remained statistically significant in 2009 to 2010 (P < 0.001). In 1992 to 1993 and 2009 to 2010, rates of PCI within 30-days of AMI differed significantly among black women (8.6% in 1992 to 1993; 24.2% in 2009 to 2010), black men (10.4% and 32.6%), white women (12.8% and 30.5%), and white men (16.1% and 40.7%) (P < 0.0001). In multivariable-adjusted analyses, racial disparities in procedure utilization appeared somewhat larger and sex-based disparities remained significant. Unadjusted 30-day mortality after AMI in 1992 to 1993 for black women, black men, white women and white men was 20.4%, 17.9%, 23.1% and 19.5%, respectively (P < 0.0001); in 2009 to 2010 mortality was 17.1%, 15.3%, 18.2% and 16.2%, respectively (P < 0.0001). In adjusted analyses, racial differences in mortality declined over time but differences by sex (higher mortality for women) persisted. Conclusions: Disparities in AMI have declined modestly, but remain a problem, particularly with respect to patient sex.