Differences in the level of inflammation among dialysis patients may explain, in part, why African Americans have better survival than Caucasians, study findings suggest.
Deidra C. Crews, MD, of Johns Hopkins University School of Medicine in Baltimore, and colleagues prospectively studied 816 dialysis patients—554 Caucasians and 262 African Americans—for a median of three years (range four months to 9.5 years). The mortality rate at five years was 34% for Africans Americans compared with 56% for Caucasians, Dr. Crews’ team reported in the Journal of the American Society of Nephrology (2011;22:2279-2286).
After adjusting for gender, age, dialysis modality, and numerous other confounders, African Americans had a 30% decreased risk of death compared with Caucasians. The risk varied by tertile of C-reactive protein (CRP), a marker of systemic inflammation. Compared with Caucasians in the first quartile of CRP level, African Americans in the third tertile had a significant 49% decreased risk of death in a fully adjusted model.
“In our model, the survival advantage among African American dialysis patients was found to only exist in the setting of high levels of inflammation,” the authors wrote. “Racial differences in the presence and response to inflammation may underlie the long-observed survival paradox seem among dialysis patients and is worthy of further investigation.”
Among dialysis patients, Africans Americans have a decreased risk of cardiovascular disease (CVD), the researchers stated, and it has been postulated that because African Americans tend to have more organ-limited kidney diseases as cause of end-stage renal disease (ESRD), such as focal segmental glomerulosclerosis, “their burden of external atherosclerosis may be less than that of Caucasians.”
They pointed out that their study found that 49% of Caucasians had CVD compared with 33% of African Americans. A lesser prevalence of CVD, the researchers said, may explain a recent report that a cohort of African Americans with moderate chronic kidney disease attributed to hypertension were more likely to progress to ESRD than die.
“Therefore, it is possible that inflammation present in African Americans with ESRD is most often due to causes other than CVD, thus potentially leading to less detrimental effects on survival,” they stated. “It is also possible that the origin of inflammation does not differ between African Americans and Caucasians, but rather the difference lies in the consequences or handling of inflammation.”