Relationship Between Medication Adherence and Distance to Dispensing Pharmacies and Prescribers Among an Urban Medicaid Population with Diabetes Mellitus.

STUDY OBJECTIVE

To determine whether a relationship exists between medication adherence to angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) and distance to dispensing pharmacies and prescribers among an urban public aid population with diabetes mellitus.

DESIGN

Retrospective cohort study using claims data.

DATA SOURCE

Illinois Department of Healthcare and Family Services database.

PATIENTS

A total of 6532 patients aged 18-64 years with diabetes who had at least one prescription fill for an ACEI or ARB and had continuous Medicaid coverage in the greater Chicago area in 2009.

MEASUREMENTS AND MAIN RESULTS

We assessed medication adherence, defined as proportion of days covered (PDC) of 0.8 or higher, to ACEIs and ARBs and its association with distances between patients and their pharmacies and prescribers. Of the 6532 patients included in the analyses, 2930 (45%) had PDC levels of 0.8 or higher. No significant differences were observed between patients who were adherent versus those who were nonadherent in distance to pharmacy (median 1.39 vs 1.35 miles, p=0.15) or distance to prescriber (median 4.39 vs 4.48 miles, p=0.80). In a multivariate regression model including age, sex, race/ethnicity, number of pharmacies, number of prescribers, distance to pharmacy, and distance to prescriber, a greater number of prescribers was associated with higher adherence (two prescribers vs one prescriber: odds ratio [OR] 1.396, 95% confidence interval [CI] 1.233-1.580; three or more prescribers vs one prescriber: OR 2.208, 95% CI 1.787-2.727).

CONCLUSION

ACEI or ARB adherence was not associated with distances to pharmacies and prescribers.