Ethnic differences in utilization of invasive cardiac procedures and in long-term survival following acute myocardial infarction

Abstract

Background: Ethnic differences in coronary mortality have been documented, and South Asians from the Indian subcontinent are particularly vulnerable. Hypothesis: This study sought to determine whether there was a difference in the utilization of invasive cardiac procedures and long-term mortality in survivors of myocardial infarction (MI) among Chinese, Malays, and South Asians in Singapore. Methods: All MI events in the country were identified and defined by the Singapore Myocardial Infarction Register, which uses modified procedures of the World Health Organization MONICA Project. Information on utilization of coronary angiography, coronary angioplasty, coronary artery bypass graft, and survival was obtained by data linkage with national billing and death registries. Hazard ratios (HR) were calculated using the Cox proportional hazards model with adjustment for baseline characteristics. Results: From 1991 to 1999, there were 10,294 patients who survived ≥3 days of MI. Of these, 40.6% underwent coronary angiography and 16.5% a revascularization procedure ≤28 days. Malays received substantially less angiography (34.0%) and revascularization (11.4%) than Chinese (41.9%, 17.9%) and South Asians (40.0%, 16.3%). The ethnic disparity increased during the 1990s, particularly in the performance of coronary angiography (p = 0.038). While fatality declined during the study period for Chinese and South Asians, the rate remained stable for Malays. After a median follow-up period of 4.1 years, survival was lowest among Malays (adjusted HR, 1.28; 95% confidence interval, 1.15-1.42, compared with Chinese). Conclusion: Ethnic inequalities in invasive cardiac procedures exist in Singapore and were exacerbated in the 1990s. Inequalities in medical care may contribute to the poorer long-term survival among Malays.