Impact of persistence with antiplatelet therapy on recurrent ischemic stroke and predictors of nonpersistence among ischemic stroke survivors.

ABSTRACT

OBJECTIVE: Medication adherence is an important component of effective secondary stroke prevention. The objectives of this study were to examine the impact of persistence with two prescription antiplatelet therapies on the outcome of recurrent hospitalized stroke, and to identify the predictors of nonpersistence with these antiplatelet therapies. RESEARCH DESIGN AND METHODS: Administrative claims from a large, geographically diverse US health plan were used to evaluate acetylsalicylic acid / extended-release dipyridamole (ASA/ERDP) treated and clopidogrel treated patients from November 1, 2002 - December 31, 2005 who had an ischemic stroke requiring hospitalization. Nonpersistence was defined as failure to refill index medication within 30 days from the run-out date of the prior prescription. A Cox proportional hazards model was used to identify key factors associated with time to nonpersistence. MAIN OUTCOME MEASURES: Patient demographic variables, clinical characteristics, comorbidities hypothesized to affect the risk of current stroke, stroke outcomes, treatment patterns, and compliance were assessed. RESULTS: A total of 1413 patients hospitalized for ischemic stroke were identified. Mean age was 63.4 years and 44.2% were female. The proportion of patients persistent per person-year was 45.1%. Persistence with medication was significantly associated with a longer time to recurrent hospitalized stroke (HR 0.275; 95% CI 0.134-0.564; p < 0.0004). A medication copayment of >$40 (relative to a copayment of < or =$20) was the only significant factor predicting time to nonpersistence (HR 1.320; 95% CI 1.091-1.596; p < 0.0042). CONCLUSIONS: Persistence with antiplatelet medication within a cohort of hospitalized ischemic stroke patients was associated with a 72.5% lower likelihood of recurrent hospitalized stroke. Higher medication copayment was found to negatively impact patient persistence with antiplatelet therapy. The findings of this study must be considered within the limitations of database analysis, as claims data are collected for the purpose of payment and not research.