Wide clinic-level variation in adherence to oral diabetes medications in the VA.

Background: While there has been extensive research into patient-specific predictors of medication adherence and patient-specific interventions to improve adherence, there has been little examination of variation in clinic-level medication adherence.

Objective: We examined the clinic-level variation of oral hypoglycemic agent (OHA) medication adherence among patients with diabetes treated in the Department of Veterans Affairs (VA) primary care clinics. We hypothesized that there would be systematic variation in clinic-level adherence measures, and that adherence within organizationally-affiliated clinics, such as those sharing local management and support, would be more highly correlated than adherence between unaffiliated clinics.

Design: Retrospective cohort study.

Setting: VA hospital and VA community-based primary care clinics in the contiguous 48 states.

Patients: 444,418 patients with diabetes treated with OHAs and seen in 158 hospital-based clinics and 401 affiliated community primary care clinics during fiscal years 2006 and 2007.

Main Measures: Refill-based medication adherence to OHA.

Key Results: Adjusting for patient characteristics, the proportion of patients adherent to OHAs ranged from 57 % to 81 % across clinics. Adherence between organizationally affiliated clinics was high (Pearson Correlation = 0.82), and adherence between unaffiliated clinics was low (Pearson Correlation = 0.04).

Conclusion: The proportion of patients adherent to OHAs varied widely across VA primary care clinics. Clinic-level adherence was highly correlated to other clinics in the same organizational unit. Further research should identify which factors common to affiliated clinics influence medication adherence.