OBJECTIVES: To examine the association between medication nonadherence and hospitalization costs among Medicare enrollees who received medications through a pharmacy assistance program.

METHODS: This study included Medicare enrollees (≥ 65 years) who received oral antidiabetic medications (OAMs) through Pharmaceutical Assistance Contract for Elderly (PACE) program of Pennsylvania in 2015 and had at least one inpatient hospital admission during 12-months from the index date (when first prescription for OAM was filled). Medication adherence was estimated as proportion of days covered (PDC) [adherent: PDC ≥ 80%, nonadherent: PDC < 80%]. The hospitalization costs (2015 USD) were calculated by applying hospital-level Medicare-specific cost-to-charge ratios (CCRs) to hospital inpatient charges obtained from Pennsylvania Health Care Cost Containment Council’s (PHC4), which included only direct charges for hospital services. General linear model with a gamma distribution and log link function was used to examine the association between medication nonadherence and hospitalization costs (all-cause and diabetes-related), while controlling for covariates such as sociodemographic characteristics, lived in a pharmacy desert or not, number of unique medications received and out-of-pocket drug costs.

RESULTS: Among 1,907 Medicare enrollees included in the study, 1,447 (73.5%) patients were adherent. Total study population cost the Medicare program $35.5 million for all-cause and $9.1 million for diabetes-related inpatient hospital admissions. The annual mean healthcare cost per patient was $18,066 and $4,416 for all-cause and diabetes-related hospitalizations respectively. All-cause hospitalization cost was significantly higher for nonadherent than adherent patients (mean $23,059 vs $16,266; p < 0.0001). GLM models showed that medication nonadherence was associated with significant increase in all-cause hospitalization costs ($22,670 vs $16,383; p < 0.0001) and diabetes-related hospitalization costs ($13,518 vs $12,634; p= 0.0003).

CONCLUSIONS: Medicare enrollees who were nonadherent to OAMs received through prescription assistance program had more hospitalization costs as compared to adherent patients.