Prescription drug spending and hospital use among Medicare beneficiaries with heart failure

Background: Heart failure (HF) is a common cause of hospitalization in Medicare. Optimal medication adherence lowers hospitalization risk in HF patients. Although out-of-pocket spending can adversely affect adherence to HF medications, it is unknown whether medication spending ultimately increases hospital use for Medicare beneficiaries with HF. Objective: To examine the association between out-of-pocket medication payments and HF-related hospital use among Medicare Part D subscribers. Methods: Retrospective analysis of the 2010-12 Medicare Current Beneficiary Survey. The sample comprised community-dwelling respondents with fee-for-service Medicare, continuous Part D coverage, and self-reported HF (n = 819 participant-year records). The effects of average out-of-pocket payment for a 30-day HF-related prescription on odds and frequency of hospitalization and total inpatient days attributable to HF were estimated. Design-adjusted models adjusted for sociodemographic and health status variables, survey year and censoring, and included a pre-specified interaction of out-of-pocket payment with Medicaid co-eligibility. Results: The interaction term was statistically significant in all the models. For beneficiaries without Medicaid, average out-of-pocket payment per prescription was not significantly associated with odds of HF-related hospitalization (odds ratio = 1.01, 95% CI = 0.98-1.05, P = .399). The association between out-of-pocket payment and hospitalization frequency was statistically significant (incidence rate ratio [IRR] = 1.02, 95% CI = 1.00-1.05, P = .048), as was the association between out-of-pocket payment and total inpatient days (IRR = 1.04, 95% CI = 1.00-1.08, P = .041). For Medicaid co-eligible beneficiaries, the validity of model estimates is limited, because the range of actual out-of-pocket payments was negligible. Conclusions: Fee-for-service Medicare beneficiaries with Part D, self-reported HF, and no supplemental Medicaid tolerated out-of-pocket medication payments without elevated risk of HF-related hospital use, but medication spending modestly increased hospital use intensity. Therefore, Part D plans with higher out-of-pocket requirements for essential HF medications may warrant additional scrutiny.