Racial and Regional Disparities in Outcomes Among Veterans Initially Adherent to Oral Antidiabetic Therapies: an Observational Cohort Study.

Background: Adherence to prescribed medications is connected with, but is not a guarantee of, improved disease management and health outcomes. It remains unclear whether underlying health disparities exist among patients adherent to therapy and whether differences in outcomes vary by race and residential areas of the country.

Objective: To determine the extent of racial and regional variation in outcomes within 5 years of oral antidiabetic drug initiation among veterans adherent to therapy.

Design: Retrospective cohort study of 83,265 US Veterans Health Administration data, 2002-2014 PATIENTS: US veterans with uncomplicated diabetes and taking oral antidiabetic agents MAIN MEASURES: Veterans initially adherent to oral antidiabetic therapy were followed for up to 5 years, and comparisons focused on differences between non-Hispanic White and non-Hispanic Black veterans across geographic region and residential type (urban or rural). Outcomes included composite cardiovascular events, composite cerebrovascular events, or all-cause mortality using Poisson and adjusted Cox proportional hazards models.

Key Results: Cardiovascular event and all-cause mortality rates differed by race and region, while urban/rural differences were evident for cerebrovascular events and all-cause mortality. For non-Hispanic Blacks, the mortality rate was half that compared to non-Hispanic Whites (6.5 [95% CI 5.8-7.2] versus 13.3 [95% CI 12.9-13.8], p < 0.0001). Compared to the Northeast, all other regions had higher adjusted hazards for cardiovascular or cerebrovascular events (with a single exception), but no regional differences in all-cause mortality were observed. Models with interactions demonstrated that racial differences in cardiovascular events and all-cause mortality were isolated to the Midwest (HR 1.99 [95% CI 1.301-3.06; HR 1.64 [95% CI 1.210-2.215]) and South (HR 1.69 [85% CI 1.347-2.131]; HR 1.27 [95% CI 1.095-1.470]).

Conclusions: Despite adherence to therapy, differences in outcomes are likely among veterans with diabetes based on race and geography. Localized analyses may uncover specific social determinants contributing to differences in outcomes.