Racial differences in inflammation and outcomes of aging among kidney transplant candidates

BackgroundInflammation is more common among African Americans (AAs), and it is associated with frailty, poor physical performance, and mortality in community-dwelling older adults. Given the elevated inflammation levels among end-stage renal disease (ESRD) patients, inflammation may be associated with adverse health outcomes such as frailty, physical impairment, and poor health-related quality of life (HRQOL), and these associations may differ between AA and non-AA ESRD patients.MethodsOne thousand three ESRD participants were recruited at kidney transplant evaluation (4/2014-5/2017), and inflammatory markers (interleukin-6 [IL-6], tumor necrosis factor-a receptor-1 [TNFR1], C-reactive protein [CRP]) were measured. We quantified the association with frailty (Fried phenotype), physical impairment (Short Physical Performance Battery [SPPB]), and fair/poor HRQOL at evaluation using adjusted modified Poisson regression and tested whether these associations differed by race (AA vs. non-AA).ResultsNon-AAs had lower levels of TNFR1 (9.7ng/ml vs 14.0ng/ml, p<0.001) and inflammatory index (6.7 vs 6.8, p<0.001) compared to AAs, but similar levels of IL-6 (4.5pg/ml vs 4.3pg/ml, p>0.9) and CRP (4.7 g/ml vs 4.9 g/ml, p=0.4). Non-AAs had an increased risk of frailty with elevated IL-6 (RR=1.58, 95% CI:1.27-1.96, p<0.001), TNFR1 (RR=1.60, 95% CI:1.25-2.05, p<0.001), CRP (RR=1.41, 95% CI:1.10-1.82, p<0.01), and inflammatory index (RR=1.82, 95% CI:1.44-2.31, p<0.001). The associations between elevated inflammatory markers and frailty were not present among AAs. Similar results were seen with SPPB impairment and poor/fair HRQOL.ConclusionsNon-AAs with elevated inflammatory markers may need closer follow-up and may benefit from prehabilitation to improve physical function, reduce frailty burden, and improve quality of life prior to transplant.