Sickle Cell Trait Among African Americans Associated With Increased Risk of Chronic Kidney Disease

In a study that included nearly 16,000 African Americans, those with sickle cell trait had an associated increased risk of chronic kidney disease and measures linked to poorer kidney function, according to a study appearing in JAMA. Sickle cell trait is a condition in which a person has only one copy of the gene for sickle cell but does not have sickle cell disease (which requires two copies of this gene). The study is being released to coincide with its presentation at the American Society of Nephrology’s annual Kidney Week meeting.

It is estimated that sickle cell trait (SCT) affects 1 in 12 African Americans and nearly 300 million people worldwide. The relationship of SCT to long-term functional impairment of the kidney has not been firmly established, according to background information in the article.

Using five large, U.S. population-based studies, Rakhi P. Naik, M.D., of Johns Hopkins University, Baltimore, and Vimal K. Derebail, M.D., of the University of North Carolina at Chapel Hill, and colleagues evaluated 15,975 self-identified African Americans (1,248 patients with SCT [SCT carriers] and 14,727 patients without SCT [noncarriers]) to examine the relationship between SCT and chronic kidney disease (CKD) and albuminuria (the presence of excessive protein in the urine, often a symptom of a kidney disorder). The studies included in the analysis were the Atherosclerosis Risk in Communities Study (ARIC); Jackson Heart Study (JHS); Coronary Artery Risk Development in Young Adults (CARDIA); Multi-Ethnic Study of Atherosclerosis (MESA); and the Women’s Health Initiative (WHI).

Chronic kidney disease (defined as a certain measure of estimated glomerular filtration rate [eGFR; the flow rate of filtered fluid through the kidney]) was present in 2,233 individuals (239 of 1,247 SCT carriers [19.2 percent) vs 1,994 of 14,722 noncarriers [13.5 percent]). A total of 20.7 percent of SCT carriers vs 13.7 percent of noncarriers experienced incident CKD. Sickle cell trait was significantly associated with a faster decline in eGFR; 22.6 percent of SCT carriers vs 19.0 percent of noncarriers from the 5 cohorts experienced eGFR decline; 31.8 percent of SCT carriers had albuminuria vs 19.6 percent of noncarriers.

“Our findings show an association of SCT with the development of CKD in African Americans,” the authors write.

The researchers add that the associations found in this study may offer an additional genetic explanation for the increased risk of CKD observed among African Americans compared with other racial groups. “Our study also highlights the need for further research into the renal complications of SCT. Because screening for SCT is already being widely performed, accurate characterization of disease associations with SCT is critical to inform policy and treatment recommendations.”