Medication adherence and healthcare disparities: impact of statin co-payment reduction.

OBJECTIVES Minority patients have lower rates of cardiovascular medication adherence, which may be amenable to co-payment reductions. Our objective was to evaluate the effect of race on adherence changes following a statin co-payment reduction intervention. STUDY DESIGN Retrospective analysis. METHODS The intervention was implemented by a large self-insured employer. Eligible individuals in the intervention cohort (n = 1961) were compared with a control group of employees of other companies without such a policy (n = 37,320). As a proxy for race, we categorized patients into tertiles based on the proportion of black residents living in their zip code of residence. Analyses were performed using difference-in-differences design with generalized estimating equations. RESULTS Prior to the new co-payment policy, adherence rates were higher for individuals living in areas with fewer black residents. In multivariable models adjusting for demographic factors, clinical covariates and baseline trends, the co-payment reduction increased adherence by 2.0% (P = .14), 2.1% (P = .15) and 6% (P < .0001) for intervention patients living in areas with the bottom, middle and top tertiles of the proportion of black residents. These results persisted after adjusting for income. CONCLUSIONS Co-payment reduction for statins preferentially improved adherence among patients living in communities with a higher proportion of black residents. Further research is needed on the impact of value-based insurance design programs on reducing racial disparities in cardiovascular care.