Why African Americans on Dialysis Live Longer than Whites

High levels of inflammation -- which may be due to conditions such as infections, inflammatory illnesses, periodontal disease, chronic lung disease, and obesity -- increase dialysis patients' risk of dying prematurely. Deidra Crews, MD (Johns Hopkins University) and her colleagues wondered whether racial differences in inflammation might explain the survival paradox among dialysis patients.

The investigators followed 554 white and 262 African American dialysis patients from 81 clinics for an average of three years (range four months to 9.5 years). Among the major findings:

• At five years, a lower percentage of African Americans (34%) died compared with whites (56%), as expected.
  
• A survival advantage for African Americans only existed among patients with high levels of inflammation.
• When comparing patients with lower levels of inflammation, African American and white patients survived for similar lengths of time.

What is it about inflammation that could lead to these findings? It's not clear yet, but the authors note that inflammation in whites may be caused mostly by heart disease, while in African Americans it may be due to other causes that have less detrimental effects on survival. (At the start of dialysis, half of whites in the study had heart disease compared with a third of African Americans.) Alternatively, African Americans and whites may simply respond differently to inflammation, which implies that some genetic trait allows African Americans to "handle" it better than whites.

"Our findings challenge the long held notion that African Americans do better than whites on dialysis. If we can determine, and somehow modify the impact of inflammation, we may be able to improve survival for all patients treated with dialysis," said Dr. Crews.

Journal of the American Society Nephrology (JASN), Dec. 2011. doi:0.1681/ASN.2011030305.