What is the Statin Possession Ratio Cut-Off Which Identifies Those at Increased Risk Following Acute Coronary Syndrome (ANZACS-QI 68)?

Abstract

More optimal dispensing of statins is associated with greater cholesterol lowering; however, it is not known whether this translates to improved outcomes following acute coronary syndrome (ACS). The aim of this study was to assess the association between various levels of statin adherence and outcomes following ACS. Patients hospitalised with ACS who underwent coronary angiography between 2014-2018 were identified from the All New Zealand ACS Quality Improvement (ANZACS-QI) registry. Medication possession ratio (MPR) was used to assess statin adherence and calculated over 1 year post-discharge using linked pharmaceutical dispensing datasets. Optimal, adequate and suboptimal adherence was defined as an MPR of ≥1.0, 0.8-0.99 and 0-0.79, respectively. A combined outcome of all-cause mortality and rehospitalisation for atherosclerotic disease was identified from 1 year post-discharge through September 2021. Cox proportional hazard models were used to adjust for confounding variables. Of the 30,452 patients, 68% had optimal adherence, 15% adequate adherence and 16% had suboptimal adherence to statins. Mean follow-up was 3.6 years. Those with suboptimal adherence had a higher adjusted risk of the combined outcome compared with those with optimal adherence (HR 1.18, 95% CI 1.11-1.26). There was no significant difference in adjusted outcome between those with optimal and adequate adherence (HR 0.99, 95% CI 0.92-1.06). Suboptimal statin adherence following ACS is associated with an increased risk of mortality and rehospitalisation. An MPR cut-off of 0.8 seems reasonable to identify those at higher risk of cardiovascular events that could benefit the most from interventions to improve statin adherence and is appropriate as a target for quality improvement programs.