Impact of a value-based formulary in three chronic disease cohorts

Value-based insurance design has been suggested as an effective approach to ensure access to highvalue medications in health insurance markets. Premera Blue Cross, a large regional health plan, implemented a value-based formulary (VBF) for pharmaceuticals in 2010 that explicitly used cost-effectiveness analysis to inform medication co-payments. This study assesses the impact of a VBF on adherence and patient and health plan expenditures on 3 chronic disease states: diabetes, hypertension, and hyperlipidemia. Interrupted time series design of employer-sponsored plans from 2006 to 2013. Beneficiaries exposed to the VBF formed the intervention group, and beneficiaries in similar plans without any changes in pharmacy benefits formed the control group. We measured medication expenditures from member, health plan, and member-plus-health plan (overall) perspectives and medication adherence as proportion of days covered. We conducted an exploratory analysis of medication utilization classifying medications according to whether co-payments moved up or down in the year following VBF implementation. For the diabetes cohort, there was a statistically significant reduction in member and overall expenditures of $5 per member per month (PMPM) and $9 PMPM, respectively. For the hypertension cohort, there was a statistically significant reduction in member expenditures of $4 PMPM and an increase in health plan expenditures of $3 PMPM. There were no statistically significant effects on hyperlipidemia cohort expenditures or on medication adherence in any of the 3 disease cohorts. Exploratory analyses suggest that patients in the diabetes and hyperlipidemia cohorts were switching to higher-value medications. A VBF can ensure access to high-value medications while maintaining affordability.