Abstract 11269: Comparing Measures of Adherence and Persistence to Ticagrelor Therapy in Patients With Acute Coronary Syndromes

Introduction: There have been efforts to accurately measure adherence to ticagrelor to identify suboptimal medication therapy in the first year post-ACS as nonadherence during this crucial period is a major obstacle to optimizing clinical outcomes. Our study aims to examine ticagrelor adherence and persistence using different methods to better understand adherence patterns. Methods: We conducted a retrospective cohort study of patients aged ≥65 years who had filled a ticagrelor prescription within 7 days post-ACS discharge in Ontario, Canada between 4/2014-3/2018. We estimated mean proportion of days covered [PDC], the proportion of patients with “good” adherence of PDC≥80%, both at 1 year and the proportion of patients who were persistently taking ticagrelor at 1-year, using permissible gaps between prescriptions of 3, 7, 14 and 30 days. Results: There were 9,763 ticagrelor users (mean age 73.6; 65.4% men). The mean 1-year PDC (±SD) was 80.8±29.2, while only 73.0% of the cohort showed good adherence (PDC≥80%). Using a permissible gap definition of 14 days, only 55.7% of patients were persistent with ticagrelor in the year post-ACS. The 1-year persistence rates were as high as 62.6% with an allowable gap of 30 days and as low as 49.7% for a 7-day gap and 39.3% for a 3-day gap. Conclusions: Adherence and persistence estimates varied widely based on the definition used. While the PDC estimates implied reasonable 1-year ticagrelor adherence, PDC methods overestimated continuous use of ticagrelor, yet persistence methods with small gaps were likely too stringent. Readers of adherence and persistence studies should pay close attention to the methods and definitions used.