Hospitalization for Myocardial Infarction with Ticagrelor or Clopidogrel in Patients with Acute Coronary Syndrome: An On-Treatment Comparative Effectiveness Analysis

INTRODUCTION: Prescribing patterns and suboptimal adherence present methodological challenges for real-world head-to-head comparisons of ticagrelor and clopidogrel in intent-to-treat studies. The aim of this study was to compare ticagrelor and clopidogrel in an on-treatment population. METHODS: This retrospective cohort study used the Optum™ Clinformatics™ database to identify patients with acute coronary syndrome (ACS) discharged on ticagrelor or clopidogrel between January 1, 2012 and September 30, 2019. The primary end point was hospitalization for myocardial infarction (MI); the secondary end point was hospitalization for major bleeding. The ticagrelor and clopidogrel cohorts were balanced by propensity score matching (PSM) 1:3 for demographic and clinical characteristics. Outcomes were ascertained from day 31 until day 365 or end of follow-up. RESULTS: Of 339,387 patients with ACS, 14,110 ticagrelor- and 57,482 clopidogrel-treated patients met the study criteria. After PSM, 13,373 ticagrelor- and 29,656 clopidogrel-treated patients provided 4945 and 13,895 patient-years of data, respectively, for the primary end point. Hospitalization for MI was significantly lower in the ticagrelor compared to the clopidogrel cohort (2.22 vs. 3.52 per 100 patient-years; 36.8% relative risk reduction [RRR]; P < 0.0001). Hospitalization for major bleeding was similar in the ticagrelor and clopidogrel cohorts (2.04 vs. 2.06 per 100 patient-years; 1.1% RRR, P = 0.9214). CONCLUSIONS: In this real-world on-treatment analysis, hospitalization for MI was significantly lower with ticagrelor compared to clopidogrel, with similar rates of hospitalization for major bleeding. Study findings underscore the importance of being on the appropriate guideline-recommended therapy and support the use of ticagrelor over clopidogrel.