3067 — Impact of Long-Term Medication Non-Adherence on Mortality Differs by Race/Ethnicity among Veterans with Diabetes
Lynch CP, Gebregziabher M, Hunt KJ, Echols C, Gilbert GE, and Egede LE, Center for Disease Prevention and Health Interventions for Diverse Populations, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC;
Medication non-adherence is linked to adverse outcomes including poor glycemic control, increased hospitalization, greater healthcare costs and higher all-cause mortality. This study examined the longitudinal effect of medication non-adherence on all-cause mortality by race/ethnicity in a national sample of Veterans with type 2 diabetes.
A longitudinal cohort of Veterans with type 2 diabetes was created by linking multiple patient and administrative files from 2 large Veterans Administration databases. The outcome was time to death, measured in months between date of study entry and date of death (or date last seen or May 2006). Predictors were race/ethnicity and mean medication possession ratio (MPR) categorized into quintiles for each Veteran. Cox regression models assessed the association between time to death and MPR and race, controlling for sociodemographics (including geographic residence), medication class (oral, insulin, or both), and medical and psychiatric comorbidities. Hazard ratios (HR) for mortality risk were computed for race and MPR quintiles, and the interaction between race and MPR was tested.
The study cohort comprised a total of 629,563 mostly male (97.8%) Veterans with type 2 diabetes followed over a 5-year period. After adjusting for covariates the HR for Veterans with MPR in the lowest versus highest MPR quintile was 12.21 (95%CI 11.89,12.55) for non-Hispanic white (NHW), 10.01 (9.18,10.91) for non-Hispanic black (NHB), 12.65 (11.10,14.43) for Hispanic, and 10.41 (9.06,11.96) for Other race Veterans. Compared to oral medication alone, combined therapy was linked to lower mortality risk among NHW 0.90 (0.89,0.92), NHB 0.91 (0.87,0.95), and Hispanics 0.88 (0.82,0.95). Comparing insulin use to oral medication alone, mortality risk was also lower among NHW 0.94 (0.93,0.96), but higher in Hispanic veterans 1.09 (1.03,1.16).
This study demonstrates clear evidence of a substantially higher mortality risk in the lowest MPR quintile relative to the highest quintile for all racial/ethnic groups; the association being strongest in NHW Veterans.
These findings suggest that novel interventions to improve medication adherence in diabetes are needed. In addition, more aggressive titration of medications and early use of combined therapy across racial groups may be warranted based on the study findings.