Background Premature discontinuation of P2Y12 inhibitor therapy has been associated with adverse cardiac events, which might be preventable by improving medication persistence. Current risk models have limited ability to predict patients at risk of P2Y12 inhibitor nonpersistence. Methods and Results ARTEMIS (Affordability and Real-World Antiplatelet Treatment Effectiveness after Myocardial Infarction Study) was a randomized, controlled trial testing the impact of a copayment assistance intervention on P2Y12 inhibitor persistence and outcomes. Among 6212 patients post myocardial infarction with a planned 1-year course of P2Y12 inhibitor therapy, nonpersistence was defined as a gap in P2Y12 inhibitor filled >30 days by pharmacy fill data. We developed a predictive model for 1-year P2Y12 inhibitor nonpersistence among patients randomized to usual care. P2Y12 inhibitor nonpersistence rates were 23.8% (95% CI, 22.7%-24.8%) at 30 days and 47.9% (46.6%-49.1%) at 1 year; the majority of these patients had in-hospital percutaneous coronary intervention. Patients who received the copayment assistance intervention had nonpersistence rates of 22.0% (20.7%-23.3%) at 30 days and 45.3% (43.8%-46.9%) at 1 year. A 53-variable multivariable model predicting 1-year persistence had a C-index of 0.63 (optimism-corrected C-index 0.58). Model discrimination did not improve with inclusion of patient-reported perceptions about disease, medication-taking beliefs, and prior medication-filling behavior in addition to demographic and medical history data (C-index 0.62). Conclusions Despite addition of patient-reported variables, models predicting persistence with P2Y12 inhibitor therapy performed poorly, thereby suggesting the need for continued patient and clinician education on the importance of P2Y12 inhibitor therapy after acute myocardial infarction. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02406677.
Keywords: P2Y12 inhibitor therapy; medical adherence; post‐myocardial infarction.