Medication Adherence and Racial Differences in A1C Control

Abstract

OBJECTIVE -The purpose of this study was to examine medication adherence and other self-management practices as potential determinants of higher glycemic risk among black relative to white patients.RESEARCH DESIGN AND METHODS -We used a retrospective, longitudinal repeated-measures design to model the contribution of medication adherence to black-white differences in A1C among type 2 diabetic patients at a large multispecialty group practice. We identified 1,806 adult (aged Ն18 at diagnosis) patients (467 black and 1,339 white) with newly initiated oral hypoglycemic therapy between 1 December 1994 and 31 December 2000. Race was identified using an electronic medical record and patient self-report. Baseline was defined as the 13 months preceding and included the month of therapy initiation. All patients were required to have at least 12 months of follow-up.RESULTS -At initiation of therapy, black patients had higher average A1C values compared with whites (9.8 vs. 8.9, a difference of 0.88; P Ͻ 0.0001). Blacks had lower average medication adherence during the first year of therapy (72 vs. 78%; P Ͻ 0.0001). Although more frequent medication refills were associated with lower average A1C values, adjustment for adherence did not eliminate the black-white gap.CONCLUSIONS -We found persistent racial differences in A1C that were not explained by differences in medication adherence. Our findings suggest that targeting medication adherence alone is unlikely to reduce disparities in glycemic control in this setting. Further research is needed to explore possible genetic and environmental determinants of higher A1C among blacks at diagnosis, which may represent a critical period for more intensive intervention.

Longitudinal Differences in Glycemic Control by Race/Ethnicity Among Veterans With Type 2 Diabetes

“…In 1 study, longitudinal repeated measures design was used to model the contribution of medication adherence to BlackWhite differences in HbA1c in patients with type 2 diabetes. 10 Mean HbA1c at baseline was higher in Black and Blacks had lower medication adherence; however, adjust- ment for medication adherence did not eliminate the BlackWhite difference in HbA1c. In the Translating Research into Action study, glycemic control was lower in Blacks and adjustment for concerns about cost, trust in physicians, smoking, and physical inactivity did not diminish the observed racial/ethnic differences in glycemic control.…”

Health Disparities in Endocrine Disorders: Biological, Clinical, and Nonclinical Factors—An Endocrine Society Scientific Statement

“…Although one study (332) suggested that an important mediator of the association between minority status and poorer glycemic control was poorer adherence to medication among NHBs and Hispanic-Americans, other research did not find this association between race and adherence (335). The lack of consistent findings suggests that more work is needed to understand the causal pathways underlying disparities in diabetes control.…”

Medication adherence and glycemic control among newly diagnosed diabetes patients

“…However, medication non-adherence is common and the benefit of the pharmaceutical therapy is discounted. A literature review indicated that of nine studies using objective measure of adherence such as medication possession ratio (MPR), seven found greater adherence was associated with improved glycemic control [9][10][11][12][13][14][15][16] ; of eight studies that evaluated hospitalization, seven showed higher adherences were associated with fewer hospitalizations 9 14 17-22 ; and of three studies that evaluated emergency department (ED) visits, two found higher adherences were associated with fewer visits. 9 17 19 In view of the chronic and progressive nature of diabetes, early medication intervention has the potential to optimize the glycemic control.…”