Effectiveness of recommended drug classes in secondary prevention of acute coronary syndrome in France

Background: Guidelines for cardiovascular secondary prevention are based on evidence from relatively old clinical trials and need to be evaluated in daily clinical practice. Objectives: To evaluate effectiveness of the recommended drug classes after an acute coronary syndrome (ACS) for secondary prevention of cardiovascular diseases and all-cause mortality. Methods: This cohort study used data from a representative sample of the French national healthcare insurance system database (EGB). Patients hospitalised for an incident ACS between 2006 and 2011, and aged ≥ 20 years at time of ACS were included in the study. Patients non-exposed to any of the four recommended drug classes (beta-blockers, antiplatelet agents, statins, and angiotensin-converting-enzyme inhibitors, ACEI, or angiotensin II receptor blockers, ARB) in the first 3 months following ACS or who died during this period were not included in the cohort. Exposure status was determined daily during follow-up. Effectiveness of the four therapeutic classes in preventing the composite outcome ACS, transient ischemic attack, ischemic stroke, or all-cause-death was estimated using a time-dependent Cox proportional hazards model, which was adjusted for time-fixed confounders measured at baseline (general characteristics and characteristics of the initial ACS) and time-dependent confounders during follow-up (co-morbidities and co-medications). Results: Of the 2874 patients included in the study, 33.9% were women and the median age was 67 years (interquartile range, IQR: 56-77). The median time of follow-up was 3.6 years (IQR: 2.2-5.3). The risk of the composite outcome decreased with use of antiplatelet agents (adjusted hazard ratio (aHR) 0.76, 95% confidence interval (CI) 0.63; 0.91), use of statins (aHR 0.71, 95%CI 0.57; 0.87), and use of ACEI/ARB (aHR 0.67, 95%CI 0.57; 0.80). Use of beta-blockers was not associated with a lower risk of the composite outcome (aHR, 0.90, 95%CI 0.74; 1.09]). Conclusions: Use of antiplatelet agents, statins, and ACEI/ARB after an ACS, but not beta-blockers, was associated with a lower risk of cardiovascular morbidity and all-cause mortality.