Role of Age and Competing Risk of Death in the Racial Disparity of Kidney Failure Incidence after Onset of CKD

Abstract

Background: The Black adult population is well known to have higher incidence of kidney failure than their White counterpart in the US, but the reasons underlying this disparity are unclear. We assessed the racial differences in kidney failure and death from onset of chronic kidney disease (CKD) based on the race-free 2021 CKD-EPI equation, and examined the extent to which these differences could be explained by factors at the time of CKD onset. Methods: A national cohort included 547,188 US veterans (103,821 non-Hispanic Black and 443,367 non-Hispanic White), aged 18-85 years, with new-onset CKD between 2005 and 2016 who were followed through 10 years or May 2018 for incident kidney failure requiring kidney replacement therapy (KFRT) and pre-KFRT death. Results: At CKD onset, Black veterans were, on average, 7.8 years younger than White veterans. In any time period from CKD onset, the cumulative incidence of KFRT was 2.5-fold higher for Black versus White veterans. Meanwhile, Black veterans had persistently >2-fold higher hazards of KFRT throughout follow-up (overall hazard ratio [95% CI], 2.38 [2.31-2.45]) and conversely had 17-48% decreased hazards of pre-KFRT death. These differences were reduced after accounting for the racial difference in age at CKD onset. Conclusions: The 2.5-fold higher cumulative incidence of kidney failure in Black adults resulted from a combination of higher hazards of progression to kidney failure and lower hazards of the competing risk of death, both of which can be largely explained by the younger age at CKD onset in Black compared to White adults.