Ethnic differences in the relationship between albuminuria and calcified atherosclerotic plaque: African American-Diabetes Heart Study

Abstract

Objective: Despite higher rates of nephropathy, calcified atherosclerotic plaque (CP) is less prevalent in African Americans (AA) with diabetes relative to European Americans (EA). We explored ethnic-specific relationships between albuminuria and CP involving the infra-renal aorta, coronary and carotid artery in 835 EA and 393 AA subjects with type 2 diabetes.

Research Design and Methods: Generalized estimating equations with exchangeable correlation and the sandwich estimator of the variance were used to test for association between the principal component of CP in the 3 vascular beds and urine albumin:creatinine ratio (ACR).

Results: Mean (SD) age of AA and EA participants was 56.7 (9.6) and 61.7 (9.1) years, respectively, diabetes duration 10.4 (7.4) and 10.0 (7.3) years, and median urine ACR 17.5 and 13.4 mg/g. In AA and EA participants, respectively, median CP mass scores were 53.5 and 291 for coronary artery, 3 and 35.5 for carotid artery, and 761 and 3237 for aorta. Adjusting for age, gender, glomerular filtration rate and body mass index, albuminuria was significantly associated with CP in EA (p=3.4 × 10⁻⁸), not in AA (p=0.33), with significant ethnic interaction (p=0.01). Ethnic differences in this relationship persisted after adjustment for blood pressure, smoking, lipids and use of angiotensin converting enzyme inhibitors or angiotensin receptor blockers.

Conclusions: Albuminuria is strongly associated with severity of CP in EA with diabetes, but not in AA. Disparities in this relationship may contribute to ethnic differences in the rates of cardiovascular disease that are observed in subjects with type 2 diabetes.