New data out last week pinpoints inflammation as a mortality risk among African Americans with ESRD. It is one more identifier presented recently in the literature that helps explain what influences survival among African Americans.

In the new paper published in the Journal of the American Society of Nephrology, "Inflammation and the paradox of racial differences in dialysis survival," principal investigator Deidra C. Crews, MD, and colleagues from Johns Hopkins University, Wake Forest University, and the University of California San Francisco, looked at the issue as to why African Americans on dialysis typically survive longer than Caucasians, but experience a higher mortality rate compared with Caucasians in the general population. A recent study by Kucirka et al. and published in the Journal of the American Medical Association in August, took a retrospective look at survivability among blacks on dialysis and found a survival advantage only among older blacks; those below 50 years of age showed a much poorly survival advantage compared to Caucasians (read a commentary on this study in NN&I's December issue).

There was some belief by researchers prior to the Kucirka study that the survivability edge among blacks was not as significant as once thought (although the data had been strong enough for the Centers for Medicare & Medicaid Services to consider a case-mix adjuster for the new bundled payment system for dialysis based on the understanding that blacks do enjoy higher survival benefits and use more anemia drugs). Some suggested there were non-clinical factors that might lead to a lower survivability among young blacks with ESRD, including social-economic issues and limited access to pre-dialysis care.

The work by Crews et al. in  the JASN study took a different direction—instead of just examining survivability data, they looked at potential causes for longer life among blacks, honing in on the influence of inflammation. They followed a national cohort of incident dialysis patients in 81 clinics for a median of three years. Among 554 Caucasians and 262 African Americans, they confirmed a 34% lower mortality among blacks after adjusting for demographics and several other covariates. However, a risk differential was noted across different subgroups delineated by inflammatory markers.  An even higher survival advantage of African Americans was noted among those with a worse inflammatory profile, whereas no survival differential existed in the lowest CRP or Interlukin-6 group, which influences inflammation. "Differences in inflammation may explain, in part, the racial paradox of ESRD survival," the researchers noted.

Despite some limitations of the study, the findings are important for nephrologists, giving them a marker to explain mortality risk among blacks, who have an incident rate of ESRD that is 3.5 times greater than non-Hispanic whites. But it also becomes a discovery that can be added to other indicators that might help reduce mortality among all dialysis patients.

Nephrologists Keith Norris and Kamyar Kalantar-Zadeh, who wrote the commentary for NN&I on the Kucirka study and also wrote an editorial on the Crews study, published in JASN this month, said "Examining these unusual disparities and paradoxes may be the key to discovering factors that can improve longevity in all CKD patients and probably in other populations with chronic disease and will be a major step to improving outcomes for all patients.  

"CRP levels can be added to a list of characteristics that may be linked to mortality, including racial/ethnic differences in nutritional and inflammatory profile and diet; differences in mineral-bone disorders, including higher parathyroid hormone levels in African-American patients leading to higher likelihood of receiving active vitamin D agents; differences in psychosocial status and coping mechanisms, including perception of quality of life; differences in dialysis treatment and techniques; and genetic or other inherent differences related to CKD and cardiovascular disease progression," they said.

With reducing risk of mortality, particularly in the first year of dialysis, being a high priority for the renal community, more studies like that of Crew et al. and Kucirka et al. can provide much needed help in reducing that risk.