Cost sharing for breast cancer hormone therapy: How do dual eligible patients’ copayment impact adherence

Objective: To examine the different levels of copayment assistance and treatment adherence among Medicare and Medicaid dual eligible beneficiaries with breast cancer in the U.S. Research design: Propensity Score methodology was adopted to minimize potential selection bias from the nonrandom allocation of the treatment group (i.e., full Medicaid beneficiaries) and control group (i.e., Medicare Savings Programs [MSPs] beneficiaries). Longitudinal hierarchical model and Cox proportional-hazard model were adopted to examine patients’ adherence over their full five-year course of adjuvant hormone therapy. Results: Our study cohort consisted of 1,133 dual eligible beneficiaries diagnosed with hormone receptor-positive early stage breast cancer in years 2007 –mid 2009. About 80.5% of them received MSPs benefits, while the rest received full Medicaid benefits. On average for a standardized 30-day hormone therapy medication, full Medicaid beneficiaries spent $0.5-$2.0 and MSP beneficiaries spent $1.4-$4.8 in copayment. After adjusting for other factors, this copayment reduction wasn’t associated with a significantly better adherence. However, when the catastrophic coverage threshold was reached (copayments reduced to zero), significant improvement in adherence was found in both groups. Conclusions: Our study found that small amount of cost-sharing reduction did not affect Medicare and Medicaid dual eligible patients’ medication treatment adherence, however, the elimination of cost-sharing (even a minimal amount) was associated with improved adherence. Future legislative and advocacy efforts should be paid on eliminating cost sharing for dual eligibles, and possibly even a broader group of financially vulnerable patients.