IMPORTANCE In the PEGASUS-TIMI 54 trial, treatment with ticagrelor reduced the incidence of cardiovascular death,myocardial infarction, or stroke by 15%to 16%among stable patients compared with placebo. However, more patients prematurely discontinued treatment with ticagrelor than with placebo. OBJECTIVE To investigate the reasons and timing of discontinuation of treatment with ticagrelor among stable patients priormyocardial infarction. DESIGN, SETTING, AND PARTICIPANTS In the PEGASUS-TIMI 54 trial, 21 162 stable outpatients with priormyocardial infarction were randomly assigned to 90mg of ticagrelor twice daily, 60mg of ticagrelor twice daily, or placebo, with all of the patients receiving a low dose of aspirin. These participants were followed up for a median of 33 months (study start date: October 2010; completion date: December 2014). Discontinuation of treatment was evaluated by treatment arm, cause, and timing. This analysis was initiated in May 2015. MAIN OUTCOME AND MEASURE Discontinuation of treatment. RESULTS Over 33 months, 32%, 29%, and 21% of patients receiving 90mg of ticagrelor, 60mg of ticagrelor, and placebo, respectively, discontinued treatment (P < .001). Discontinuation of treatment due to an adverse event occurred in 19%, 16%, and 9% of patients, respectively (P < .001). The most frequent adverse events leading to discontinuation of treatment were bleeding (with Kaplan-Meier event rates of 7.8%, 6.2%, and 1.5%of patients, respectively; P < .001) and dyspnea (6.5%, 4.6%, and 0.8%of patients, respectively; P < .001). Eighty-six percent of bleeding events that led to the discontinuation of treatment with ticagrelor were nonmajor, and 86%of adverse events due to dyspnea that led to discontinuation of treatment with ticagrelor were mild or moderate in severity. The discontinuation rates are annualized for patients who received 90mg of ticagrelor twice daily (hazard ratio [HR], 2.00 [95%CI, 1.84-2.16] for the first year; HR, 1.12 [95%CI, 1.00-1.26] for the second and third years) and patients who received 60mg of ticagrelor twice daily (HR, 1.59 [95%CI, 1.46-1.73] for the first year; HR, 1.18 [95%CI, 1.06-1.32] for the second and third years) compared with patients who received placebo. CONCLUSIONS AND RELEVANCE When initiated among stable patients with priormyocardial infarction, discontinuation of treatment with ticagrelor was driven primarily by nonserious adverse events occurring primarily early after randomization. For patients completing 1 year of treatment, the subsequent discontinuation rate was low. These data demonstrate how adverse events considered "nonserious" by traditional trial criteria may have an effect on quality of life and, thus, may precipitate the discontinuation of treatments and underscore the need for patient education and counseling on the timing and nature of adverse effects with the aim of improving adherence when appropriate.
