JAMA: 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.”
(doi:10.1001/jama.2014.15063; Available pre-embargo to the media at http://media.jamanetwork.com)
Editor’s Note: Please see the article for additional information,
including other authors, author contributions and affiliations,
financial disclosures, funding and support, etc.