OBJECTIVES: Blue Cross Blue Shield of Louisiana (Blue Cross)’s Zero Dollar Copay (ZDC) program removes the copay for a large set of medications related to certain chronic diseases. We aimed to evaluate the effects of the ZDC program on medication adherence by drug class and socioeconomic status.

METHODS: We analyzed Blue Cross members aged 18 years and above who were continuously enrolled in a chronic disease management (DM) program (asthma, chronic obstructive pulmonary disease, coronary heart disease, hypertension, diabetes, or chronic kidney disease) from March 2017 to March 2019. The ZDC treatment cohort was comprised of fully-insured members who had Blue Cross pharmacy benefit that included copays. Members without a copay or who were covered by employers contracting for administrative services only were included in the control group. All study participants were taking ZDC program-related drugs during the study period with at least 1 month of claims following ZDC enrollment. Propensity score weighting was performed to control for several baseline factors, and difference-in-difference (DID) regression models were used to measure program effects.

RESULTS: Adherence rates in the ZDC cohort increased for most drug classes compared to the control group, and the largest DIDs were observed for diuretics (8.4%), anti-diabetics (6.2%), and calcium channel blockers (6.1%). Across all income levels, average medication adherence increased for members in the ZDC group relative to controls. Members in the lowest income bracket (income between $0 and $39,000) showed the greatest improvement in medication adherence compared to other income groups, with average rates increasing by 1.2% in the ZDC group and decreasing by 2.4% in the control group.

CONCLUSIONS: The ZDC program increased medication adherence rates relative to controls, an effect that was primarily driven by members with lower socioeconomic status.