COMMENTARY

Diabetes and Progression of CKD: Does Race Matter?

Nisha Bansal, MD, MAS

Disclosures

July 25, 2018

As the rates of type 2 diabetes continue to rise in the United States and worldwide, the rates of diabetes-related complications such as kidney disease are expected to rise as well. Numerous studies have shown that diabetes and kidney disease disproportionately affect patients who are black.

Copious reasons for this disparity have been hypothesized, including genetic predisposition (particularly with recent discovery of apolipoprotein L1), obesity, low socioeconomic status, high-risk health behaviors (such as poor diet), and limited access to healthcare.

However, a recent study by Gerber and colleagues, published in the Clinical Journal of the American Society of Nephrology ,[1] suggests that these disparities in the rates of kidney disease among black patients with diabetes are potentially overcome with delivery of standardized care for patients with type 2 diabetes.

In this study, the authors performed a post-hoc analysis of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. The ACCORD trial was a randomized, multicenter, double 2 x 2 factorial, parallel treatment trail that enrolled over 10,000 high-risk participants with type 2 diabetes. The trial evaluated the effects of intensive versus standard glycemic control, fibrates versus placebo, and intensive versus standard BP control on major cardiovascular events. All participants in the trial were treated in a standardized manner throughout the duration of the trial. In the present analysis, the authors included the 8309 ACCORD trial participants who self-identified as non-Hispanic black (n = 1937) and non-Hispanic white (n = 6372).

Race was the primary exposure. The outcomes of interest included longitudinal change in estimated glomerular filtration rate (eGFR), time to development of microalbuminuria, macroalbuminuria, incident chronic kidney disease (CKD), and kidney failure or serum creatinine > 3.3 mg/dL.

The study included 1937 black participants and 6372 white participants. Black participants had slightly higher systolic blood pressure (139 vs 135 mm Hg), higher hemoglobin A1c (8.5 vs 8.2%), and higher prevalence of retinopathy (16 vs 10%), microalbuminuria (28 vs 25%), and macroalbuminuria (8 vs 6%). Black participants also had higher eGFR at baseline compared with whites (87 vs 83 mL/min/1.73 m2).

Although the mean values of systolic blood pressure and hemoglobin A1c were higher in blacks, both blacks and whites achieved similar rapid improvement of both clinical parameters, which were maintained during study follow-up. In multivariable models, the mean annualized change in eGFR in the first 24 months and after 24 months did not differ between black and white participants (-3.91 vs -4.10 and -0.38 vs -0.43 mL/min/1.73 m2 per year, respectively).

Furthermore, over a median follow-up of 4.4-4.7 years, black race was not associated with greater risk of development of microalbuminuria (adjusted HR, 1.05, 95% CI, 0.90-1.22), macroalbuminuria (adjusted HR, 1.15, 95% CI, 0.91-1.47), or kidney failure (adjusted HR 0.90, 95% CI: 0.63, 1.27). The risk for incident CKD was lower in black versus white participants (adjusted HR, 0.73; 95% CI, 0.57-0.92).

Standardized Care Can Reduce Racial Disparities in Diabetic Kidney Disease

Thus, in this post-hoc analysis of the ACCORD trial, in which participants all received standardized care, the results show that contrary to prior studies, black race is not associated with greater risk for kidney disease in patients with type 2 diabetes. This suggests that optimization of the delivery of diabetes care prior to the development of CKD may lead to similar short-term kidney outcomes, irrespective of race.

In this study, despite having more risk factors for poor kidney outcomes, the rates of these outcomes were largely similar among blacks and whites with implementation of a standardized treatment regimen. This has important implications as clinicians and policy makers aim to reduce rates of diabetes and diabetes complications, particularly for high-risk groups such as blacks. The goal should be to delivery optimal, high-quality healthcare across all persons to reduce disparities in outcomes by race.

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