Use of secondary prevention medications in metropolitan and non-metropolitan areas: an analysis of 41 925 myocardial infarctions in Australia.

Abstract

People in remote areas may have more difficulty accessing healthcare following myocardial infarction (MI) than people in metropolitan areas. We determined whether remoteness was associated with initial and 12-month use of secondary prevention medications following MI in Victoria, Australia. We included all people alive at least 90 days after discharge following MI between July 2012 and June 2017 in Victoria, Australia (n = 41 925). We investigated dispensing of P2Y12 inhibitors (P2Y12i), statins, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (ACEIs/ARBs), and beta-blockers within 90 days after discharge. We estimated 12-month medication use using proportion of days covered (PDC). Remoteness was determined using the Accessibility/Remoteness Index of Australia (ARIA). Data were analysed using adjusted parametric regression models stratified by ST elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI). There were 10 819 STEMI admissions and 31 106 NSTEMI admissions. Following adjustment across NSTEMI and STEMI, there were no medication classes dispensed in the 90-day post-discharge that differed in a clinically significant way from the least remote (ARIA = 0) to the most remote (ARIA = 4.8) areas. The largest difference for NSTEMI was ACEI/ARB, with 71% (95% confidence interval 70-72%) vs. 80% (76-83%). For STEMI, it was statins with 89% (88-90%) vs. 95% (91-97%). Predicted PDC for STEMI and NSTEMI was not clinically significant across remoteness, with the largest difference in NSTEMI being P2Y12i with 48% (47-50%) vs. 55% (51-59%), and in STEMI, it was ACEI/ARB with 68% (67-69%) vs. 76% (70-80%). Remoteness does not appear to be a clinically significant driver for medication use following MI. Possible differences in cardiovascular outcomes in metropolitan and non-metropolitan areas are not likely to be explained by access to secondary prevention medications.