Abstract 10843: P2Y12 Inhibitor Adherence Patterns in Patients with Acute Coronary Syndrome

Abstract

Introduction: Dual antiplatelet therapy with P2Y12 inhibitors (P2Y12i) and ASA reduce cardiac events after acute coronary syndrome (ACS). Use has shifted from clopidogrel to ticagrelor, a more potent P2Y12i with higher bleeding risk, dosed twice rather than once daily. As these factors may impact adherence, a better understanding of adherence patterns by agent is needed. Methods: We conducted a population-based cohort study using administrative claims data in Ontario, Canada between 4/2014-3/2018. We identified individuals ≥65 years of age who were admitted for myocardial infarction or unstable angina and had filled a P2Y12i prescription within 7 days of discharge. We excluded patients who died within 1 year after discharge. We calculated “good” adherence [proportion of days covered (PDC) 1 year post-ACS ≥80%, and also used group-based trajectory models to characterize longitudinal patterns of good adherence by time over 1 year. Results: We included 21,680 ACS patients with 45.0% (n=9,763) prescribed ticagrelor and 55.0% (n=11,917) prescribed clopidogrel [mean age±SD: 73.6±6.8/77.3±8.3 years, 65.4%/56.2% male, PCI during index admission 87.4%/48.5%, respectively]. Overall, the good adherence rate was 73.0% for ticagrelor and 78.9% for clopidogrel. We identified 3 adherence patterns in the year post-ACS: 67.8% of ticagrelor and 75.0% of clopidogrel patients were in the adherent group (PDC≥80%), while 17.1 %/13.4% were in the gradually non-adherent, and 15.1%/11.6% were in the rapidly non-adherent groups, respectively. (Figure) Conclusions: Adherence rates and trajectories appeared more favorable for clopidogrel in the first year post-ACS. However, patient characteristics differed between the clopidogrel and ticagrelor populations and these may be associated with the observed adherence patterns. Identification of nonadherence risk factors and barriers specific to each trajectory group is needed to improve adherence and clinical outcomes.