Utilization of evidence-based therapy for the secondary prevention of acute coronary syndromes in Australian practice

Abstract

To review and document the current utilization of pharmacotherapy for the secondary prevention of acute coronary syndromes (ACS) in patients discharged from an Australian hospital. A retrospective cross-sectional study was conducted at a major Sydney teaching hospital. Patients with either a primary or secondary diagnosis of acute coronary syndrome were identified from medical records over a 4-month period (January-April 2007). A range of clinical data was extracted from medical records, including medical history, clinical presentation and pharmacotherapy both on admission and at discharge. This audit focussed on the use of four guideline-recommended therapies: aspirin +/- clopidogrel, beta blockers, statins and ACE-inhibitors (ACE-I), as well as the utilization of multiple antithrombotics. Data pertaining to a total of 169 patients was extracted and reviewed. The mean age of the study population was 65.9 years and 71% of the population was male. Non-ST-segment elevation myocardial infarction (Non-STEMI) accounted for 42% of the admissions, whereas 33.7% and 24.3% of the patients were respectively admitted for ST-segment elevation myocardial infarction (STEMI) or unstable angina. After accounting for reported contra-indications, overall, 96% of the eligible patients received antithrombotics comprising of at least aspirin, and 79% of eligible patients received aspirin plus clopidogrel. Furthermore, 82% of eligible patients received a beta-blocker at discharge, 86% a statin and 79% received either an ACE-I or angiotensin-II receptor antagonist. Compared with patients who presented with myocardial infarction (with or without ST-segment elevation), those presenting with unstable angina were less likely to receive a beta-blocker (OR = 0.19, 95%-CI: 0.08-0.48) or an ACE-agent (OR = 0.15, 95%-CI: 0.06-0.39) at discharge. Patients over 65 years of age were also less likely to receive a beta-blocker (OR = 0.35, 95%-CI: 0.14-0.89) or an ACE-agent (OR = 0.28 95%-CI: 0.11-0.70) at discharge, but were also less likely to receive the combination of aspirin plus clopidogrel (OR = 0.19, 95%-CI: 0.07-0.54) at discharge, compared with younger patients. Men were more likely to be discharged on a statin (OR = 3.36, 95%-CI: 1.11-10.15), compared with women. Only six patients (4%) received three or more antithrombotics at discharge; five of these received the triple combination of aspirin, clopidogrel and warfarin. There is a good adherence to evidence-based guidelines for the secondary prevention of ACS in this local setting. However, there is some potential underutilization in the older population and patients presenting with unstable angina. Variability in the use of oral anticoagulants alongside dual antiplatelet therapy indicates there is potentially a need for further guidance regarding the prescription of antithrombotics in those requiring poly-therapy.