Background: Patient and hospital characteristics influence the use of invasive cardiac procedures. Whether socioeconomic status (SES) has an influence that is independent of these other determinants is unclear. The purpose of the present study was to examine the influence of household income as a measure of SES on the use of invasive cardiac procedures among a large group of patients with acute myocardial infarction.
Methods and results: We analyzed administrative discharge data from 231 nonfederal acute care hospitals in New York State that involved 28 698 black or white inpatients with International Classification of Diseases, Ninth Revision, Clinical Modification code 410.XX in the principal diagnosis position between January 1 and December 31, 1995. Household income was derived from postal ZIP codes and census data. The use of cardiac catheterization, PTCA, CABG, and any revascularization procedure was examined across groups stratified by income. Patients who resided in lower-income neighborhoods were more often female or black, had a higher prevalence of coexistent illness, had a higher use of Medicaid insurance, and were less often admitted to urban hospitals or hospitals that provide on-site CABG and PTCA. Crude and adjusted odds ratios for catheterization, PTCA, CABG, and any revascularization procedure were related to income in a graded fashion. After adjustment, patients in the highest quintile of income were 22% more likely to undergo catheterization, 74% more likely to undergo PTCA, 48% more likely to undergo CABG, and 76% more likely to undergo any revascularization procedure than were patients in the lowest quintile. The difference in cardiac catheterization did not fully account for income-based differences in revascularization, because income remained a significant determinant of revascularization after accounting for whether a catheterization was performed. Even among patients treated in hospitals that provide on-site CABG and PTCA, income was a significant determinant of procedures.
Conclusions: Lower-income patients hospitalized for acute myocardial infarction are more often female or black, have more coexisting illnesses, and are less often admitted to urban hospitals or hospitals that provide CABG and PTCA. Even after adjustment for these and other factors, lower income is a negative predictor of procedure use.