Association Between Medication Adherence and Healthcare Costs Among Patients Receiving the Low-Income Subsidy.

OBJECTIVES

Significant literature exists on the effects of medication adherence on reducing healthcare costs, but less is known about the effect of medication adherence among Medicare low-income subsidy (LIS) recipients. This study examined the effects of medication adherence on healthcare costs among LIS recipients with diabetes, hypertension, and/or heart failure.

METHODS

This retrospective study analyzed Medicare claims data (2012-2013) linked to the Area Health Resources Files. Using measures developed by the Pharmacy Quality Alliance, adherence to 11 medication classes was studied among patients with 7 possible combinations of the diseases mentioned. Adherence was measured in 8 categories of proportion of days covered (PDC): ≥95%, 90% to <95%, 85% to <90%, 80% to <85%, 75% to <80%, 50% to <75%, 25% to <50%, and <25%. Annual Medicare costs were compared across adherence categories. A generalized linear model was used to control for patient/community characteristics.

RESULTS

Among patients with only one disease, such as diabetes, patients with the lowest adherence (PDC < 25%) had $3152/year higher Medicare costs than patients with the highest adherence (PDC ≥ 95%; $11 101 vs $7949; P < .05). The adjusted costs among patients with PDC < 25% was $1893 higher than patients with PDC ≥ 95% ($9919 vs $8026; P < .05). Among patients with multiple chronic conditions, patients' adherence to medications for fewer diseases had higher costs.

CONCLUSIONS

Greater medication adherence is associated with lower Medicare costs in the Medicare LIS population. Future policy affecting the LIS program should encourage better medication adherence among patients with chronic diseases.