Medication Nonadherence Among Medicare Beneficiaries with Comorbid Chronic Conditions: Influence of Pharmacy Dispensing Channel

BACKGROUND: Taking medications as prescribed is imperative for their effectiveness. In populations such as Medicare, where two thirds of Medicare beneficiaries have at least 2 or more chronic conditions requiring treatment with medications and account for more than 90% of Medicare health care spend, examining ways to improve medication adherence in patients with comorbidities is warranted. OBJECTIVE: To examine the association of pharmacy dispensing channel (home delivery or retail pharmacy) with medication adherence for Medicare patients taking medications with comorbid conditions of diabetes, hypertension, and high blood cholesterol (3 of the top 5 most prevalent conditions), while controlling for various confounders. METHODS: A retrospective analysis was conducted using de-identified pharmacy claims data from a large national pharmacy benefits manager between October 2010 and December 2012. Continuously eligible Medicare Part D patients (Medicare Advantage Prescription Drug plan and Prescription Drug Plan only) aged 65 years or older who had an antidiabetic, antihypertensive, and antihyperlipidemic prescription claim between October and December 2010 were identified and analyzed over a 2-year period. Multivariate logistic regression was used to evaluate the association between dispensing channel (DC) and medication adherence in calendar year (CY) 2012 controlling for prior adherence behavior (adherence in CY2011), differences in demographics, low-income subsidy status, days supply, disease burden, and drug-use pattern. Patients with a proportion of days covered (PDC) of at least 80% for each of the 3 conditions were considered to be adherent, and patients with PDC less than 80% for each of the 3 conditions were considered to be nonadherent. Patients were assigned to a DC depending on where they filled at least 66.7% of their prescriptions for each of the 3 conditions, and the rest were assigned to a mixed channel group. RESULTS: The final analytical sample consisted of 40,632 patients. The adjusted odds of adherence for patients using home delivery were 1.59 (95% CI = 1.40-1.80) higher compared with patients using retail channels to obtain their prescriptions. CONCLUSIONS: Medicare Part D patients taking medications for comorbid conditions who used home delivery had a greater likelihood (adjusted) of adherence than patients who filled their antidiabetic, antihypertensive, and antihyperlipidemic prescriptions using retail channels. Managed care stakeholders looking to make informed decisions in a cost-constrained environment to assess, implement, and promote solutions that improve health outcomes should consider the use of home delivery of prescriptions to improve adherence for Medicare Part D patients with comorbid conditions.