Socioeconomic Inequalities in Quality of Care and Outcomes Among Patients With Acute Coronary Syndrome in the Modern Era of Drug Eluting Stents

Abstract

Background The rapidly changing landscape of percutaneous coronary intervention provides a unique model for examining disparities over time. Previous studies have not examined socioeconomic inequalities in the current era of drug eluting stents ( DES ). Methods and Results We analyzed 835 070 hospitalizations for acute coronary syndrome ( ACS ) from the Healthcare Cost and Utilization Project across all insurance types from 2008 to 2011, examining whether quality of care and outcomes for patients with ACS differed by income (based on zip code of residence) with adjustment for patient characteristics and clustering by hospital. We found that lower‐income patients were less likely to receive an angiogram within 24 hours of a ST elevation myocardial infarction ( STEMI ) (69.5% for IQ 1 versus 73.7% for IQ 4, P <0.0001, OR 0.79 [0.68 to 0.91]) or within 48 hours of a Non‐ STEMI (47.6% for IQ 1 versus 51.8% for IQ 4, P <0.0001, OR 0.86 [0.75 to 0.99]). Lower income was associated with less use of a DES (64.7% for IQ 1 versus 71.2% for IQ 4, P <0.0001, OR 0.83 [0.74 to 0.93]). However, no differences were found for coronary artery bypass surgery. Among STEMI patients, lower‐income patients also had slightly increased adjusted mortality rates (10.8% for IQ 1 versus 9.4% for IQ 4, P <0.0001, OR 1.17 [1.11 to 1.25]). After further adjusting for time to reperfusion among STEMI patients, mortality differences across income groups decreased. Conclusions For the most well accepted procedural treatments for ACS , income inequalities have faded. However, such inequalities have persisted for DES use, a relatively expensive and until recently, controversial revascularization procedure. Differences in mortality are significantly associated with differences in time to primary PCI , suggesting an important target for understanding why these inequalities persist.