Premature Clopidogrel Discontinuation After Drug-Eluting Stent Placement in a Large Urban Safety-Net Hospital

Abstract

Premature clopidogrel discontinuation is an important cause of stent thrombosis, myocardial infarction, and death after drug-eluting stent (DES) placement. Previous studies of clopidogrel nonadherence after DES placement have had short follow-up and have relied on self-reported adherence. All patients who underwent DES placement from January 2008 to December 2011 at a single safety-net hospital and received medications through the county-subsidized health plan were considered for inclusion; those with <1-year follow-up were excluded. We retrospectively collected 1-year refill data from a large, closed pharmacy system. Our primary outcome was time to failure to obtain a clopidogrel refill, allowing a 5-day grace period. Our study cohort (n = 369) was 34% female, 39% Hispanic, 26% white, and 26% African-American; 26% identified Spanish as their primary language. The time to failure to obtain a clopidogrel refill was 153 days. Cumulative failure to obtain at least 1 refill was 23% for the first refill, increasing to 52% at 6 months and 68% at 1 year. Examining the proportion of days covered (PDC), 21% of patients had 100% coverage, whereas 34% had PDC <80%. There were no independent predictors of nonadherence (PDC <80%). In conclusion, we identified a high rate of clopidogrel nonadherence in a multiethnic urban poor patient population where clopidogrel was provided at discharge and at nominal cost thereafter. In this cohort, prediction models of nonadherence performed poorly. Novel strategies are needed to address this important problem.