OBJECTIVES: While State Pharmaceutical Assistance Programs (SPAPs) have potential to improve medication adherence by providing medications at little or no cost to income-eligible patients, currently there is limited information regarding factors affecting medication adherence among their elderly beneficiaries. The purpose of the study was to identify the predictors of medication adherence among elderly with diabetes who were enrolled in a SPAP.

METHODS: Pennsylvania’s Pharmaceutical Assistance Contract for the Elderly (PACE) programs’ database was used to identify patients (≥ 65 years) who received oral antidiabetic medications (OAMs) in 2015. Medication adherence was estimated as proportion of days covered (PDC) for 12-months post-index observation period (adherent: PDC ≥ 80% and nonadherent: PDC < 80%). Multiple logistic regression was used to determine the predictors of medication adherence.

RESULTS: Total 9,497 patients were included in the study. Compared to Whites, African American patients (OR= 0.583, 95% CI: 0.465,0.732, p < 0.0001) and patients with missing information on race (OR= 0.650, 95% CI: 0.513, 0.823, p=0.0004) were less likely to be adherent to OAMs. Similarly, married patients were less likely to be adherent to medications than single/widowed patients (OR=0.850, 95% CI: 0.728-0.992, p=0.0395). The patients who filled prescriptions for a greater number of unique medications (OR= 1.025, 95% CI: 1.013, 1.037, p < 0.0001) and paid higher out-of-pocket payment (OR= 1.151, 95% CI: 1.115, 1.187, p < 0.0001) were more likely to be adherent. The adherence to oral antidiabetic medication was not significantly related to age, sex, being other race, income, being divorced or married but living separately and whether patient lived in a pharmacy desert or not.

CONCLUSIONS: Race, marital status, total number of unique medications and out-of-pocket drug cost are the significant predictors of adherence to OAMs among elderly SPAP enrollees. This should be considered while initiating the treatment.