Does the Diabetes Health Plan Have a Differential Impact on Medication Adherence Among Beneficiaries with Fewer Financial Resources?

Abstract Background: The Diabetes Health Plan (DHP), a value-based insurance plan that reduces cost sharing, was previously shown to modestly increase employer-level medication adherence. However, it is unclear whether the DHP has a larger impact on individual-level medication adherence among lower- or higher-income beneficiaries. Methods: An employer-level propensity score match was done to identify suitable control employers, followed by individual-level propensity score weighting. These weights were applied to difference-in-difference (DID) models examining 1) the effect of the DHP and 2) the effect of income on changes in adherence to metformin, statins, and ACE/ARBs. The weights were then applied to a differences-in-differences-in-differences (DDD) model to estimate the differential impact of DHP status on changes in adherence by income group. This is a retrospective, quasi-experimental study.Results: There were no significant differences in changes to adherence for any medications between beneficiaries enrolled in the DHP versus standard plans. However, changes in adherence were higher for all medications among those in the highest income strata (>$75,000) versus those in the lowest income strata (<$50,000; p < 0.01). Finally, the DDD term examining the impact of income on the DHP effect was not significant for any comparisons. Conclusion: We did not find significant associations between the DHP and changes in individual-level medication adherence, even for low-income beneficiaries. New strategies to improve consumer engagement may be needed in order to translate value-based insurance designs into changes in patient behavior.