RESUMEN
BACKGROUND: Cost-sharing requirements employed by health insurers to discourage the unnecessary use of medications may lead to underutilization of recommended treatment regimens and suboptimal quality of care. Value-based insurance design (VBID) programs seek to address these problems by lowering copayments to promote adherence to "high-value" medications that have been proven to be clinically beneficial. VBID evaluations to date have focused on programs implemented by self-insured employers. This study is among the first to assess the VBID program of a health plan. METHODS: We examined a VBID program for statins implemented by a large regional health plan in 2008 and assessed its effect on medication adherence. Copayments on VBID brand statins were reduced by 42.9% for employer-sponsored plans (the treatment group) and increased by 16.7% for state-sponsored plans (the control group) between the preintervention and postintervention periods. Propensity score weights were used to balance the treatment and control groups on observed characteristics. We evaluated the impact of the VBID program on adherence using an econometric model with a difference-in-difference design. RESULTS: Medication adherence increased 2.7 percentage points (P=0.033) among VBID brand statin users in the treatment group relative to the control group. With a baseline adherence rate of 77.6%, nonadherence was reduced by 11.9%. CONCLUSIONS: Copayment reductions on selected statin medications contributed to improvements in adherence. As one of the first studies to evaluate a health plan's VBID program, our findings demonstrate that insurer-based VBID programs may yield results similar to those achieved by employer-based programs.