Study Shows Premature Clopidogrel Discontinuation After DES in a Poor, Urban Patient Population

December 7, 2015—Noting that premature clopidogrel discontinuation is an important cause of stent thrombosis, myocardial infarction, and death after drug-eluting stent (DES) placement, Houman Khalili, MD, et al conducted an investigation of this problem in a large, urban safety-net hospital. They published the findings online ahead of print in the American Journal of Cardiology.

According to the investigators, previous studies of clopidogrel nonadherence post-DES have had short follow-up and have relied on self-reported adherence. In this study, all patients who underwent DES placement between January 2008 and 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.

As summarized in the American Journal of Cardiology, the investigators retrospectively collected 1-year refill data from a large, closed pharmacy system. The primary outcome was time to failure to obtain a clopidogrel refill, allowing a 5-day grace period. The 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, while 34% had PDC < 80%. There were no independent predictors of nonadherence (PDC < 80%). 

The investigators concluded that there was a high rate of clopidogrel nonadherence in a multiethnic, urban, poor patient population where clopidogrel was provided at discharge and at nominal cost thereafter. They noted that in this cohort, prediction models of nonadherence performed poorly. Novel strategies are needed to address this important problem, advised the investigators in the American Journal of Cardiology.