Patient Race/Ethnicity, Socioeconomic Status, and Acute Myocardial Infarction Mortality

BACKGROUND: Prior work often finds racial/ethnic differences in mortality following acute myocardial infarction (AMI), but is subject to selection bias. Similar selection issues arise for differences associated with socioeconomic status (SES). OBJECTIVES: Re-examine the association between patient race/ethnicity, area-level socioeconomic status (area-SES), and post-AMI mortality using a data source that limits patient selection of hospital or cardiologist, or vice-versa, and which lets us distinguish between-hospital from within-hospital sources of differences. RESEARCH DESIGN: We compare mortality disparities with no controls, with controls typical of the prior literature ("typical controls"), and more extensive controls, including hospital, cardiologist, and calendar quarter fixed effects (FEs). SUBJECTS: The study uses a 100% sample of 681,000 Medicare Fee-for-Service patients aged 68+ hospitalized for incident (first) AMI over 2008-2019. MEASURES: Post-AMI mortality in-hospital, within 30 days after discharge and over periods up to 3 years post-discharge. We study patients with ST-segment elevation MI (STEMI) and non-ST-segment elevation MI (nSTEMI) separately. RESULTS: With no or typical controls, Blacks, Hispanics, and Asians have higher in-hospital mortality than Whites; lower SES also predicts higher mortality. However, higher mortality is substantially explained by between-hospital differences in mortality rates. Longer-term mortality is higher for Black patients, consistent with the importance of post-discharge pathways. CONCLUSIONS: Post-AMI disparities in outcomes can be strongly affected by selection effects, especially the tendency for poor and minority persons to be treated at lower-quality hospitals. Disparities measurement and policy discussions should distinguish access-related hospital sorting from within-hospital processes and pay greater attention to post-discharge pathways.