OBJECTIVES : We assessed association between drug coverage type and out-of-pocket medication cost (OOP) with cost-related nonadherence (CRN) among Medicare population with RA.

METHODS : A pooled cross-sectional analysis of 2009-2013 Medicare Current Beneficiary Survey (MCBS) data was conducted. Inclusion criteria were being 65 y/o and having RA. Exclusion criteria were being institutionalized, nonresponse on any CRN questions, or no RA-medication use. RA was identified based on ≥1 Medicare Part A or ≥2 Part B claims with ICD-9-CM: 714.x or self-report of a doctor saying they had RA.

Drug coverage type included no coverage, stand-alone Medicare prescription drug plan (PDP), Medicare Advantage Prescription Drug (MAPD) plan, PDP plus Medicaid, MADP plus Medicaid, TRICARE, and private plans. CRN was identified if there was a yes to any of the four questions: 1) whether taking smaller doses or 2) skipped doses to make the medication last longer; 3) delayed getting a prescription filled or 4) decided not to fill a prescription because of cost. Weighted multivariable logistic regression in SAS 9.4 for Unix assessed association between risk factors and CRN adjusting for age, gender, employment, smoking status, activities of daily living, instrumental activities of daily living, perceived health, osteoporosis, and depression with an alpha of 0.05 for significance.

RESULTS : In the 1,843 person-years sample, 14.6% had CRN. Monthly OOP was not associated with CRN, but patients with OOP ≥5% of income were 2.3 [1.2-4.4] times more likely to report CRN than those with <1% of income (p<0.01). Patients with MADP plus Medicaid (0.18 [0.05-0.71], p=0.01), TRICARE (0.12 [0.02-0.76], p=0.02), or private plans (0.43 [0.26-0.73], p<0.01) were less likely to report CRN than those without drug coverage.

CONCLUSIONS : Spending a higher proportion of income on OOP was associated with greater likelihood of CRN. Even after adjusting for OOP, some drug coverage types were associated with lower risk of CRN.