Donor-Recipient Relationship and Risk of ESKD in Live Kidney Donors of Varied Racial Groups

Rationale & Objective Risk factors for kidney failure are the basis of live kidney donor candidate evaluation. We quantified risk for end-stage kidney disease (ESKD) by the biological relationship of the donor to the recipient, a risk factor that is not addressed by current clinical practice guidelines. Study Design Retrospective cohort study. Setting & Participants A cohort of 143,750 US kidney donors between 1987 and 2017. Exposure Biological relationship of donor and recipient. Outcome ESKD. Donors' records were linked to national dialysis and transplantation registries to ascertain development of the outcome. Analytic Approach Donors were observed over a median of 12 (interquartile range, 6-18; maximum, 30) years. Survival analysis methods that account for the competing risk for death were used. Results Risk for ESKD varied by orders of magnitude across donor-recipient relationship categories. For Asian donors, risks compared with unrelated donors were 259.4-fold greater for identical twins (95% CI, 19.5-3445.6), 4.7-fold greater for full siblings (95% CI, 0.5-41.0), 3.5-fold greater for offspring (95% CI, 0.6-39.5), 1.0 for parents, and 1.0 for half-sibling or other biological relatives. For black donors, risks were 22.5-fold greater for identical twin donors (95% CI, 4.7-107.0), 4.1-fold for full siblings (95% CI, 2.1-7.8), 2.7-fold for offspring (95% CI, 1.4-5.4), 3.1-fold for parents (95% CI, 1.4-6.8), and 1.3-fold for half-sibling or other biological relatives (95% CI, 0.5-3.3). For white donors, risks were 3.5-fold greater for identical twin donors (95% CI, 0.5-25.3), 2.0-fold for full siblings (95% CI, 1.4-2.8), 1.4-fold for offspring (95% CI, 0.9-2.3), 2.9-fold for parents (95% CI, 2.0-4.1), and 0.8-fold for half-sibling or other biological relatives (95% CI, 0.3-1.6). Limitations Insufficient sample size in some race and relationship groups. Absence of data for family history of kidney disease for donors biologically unrelated to their recipients. Conclusions Marked differences in risk for ESKD across types of donor-recipient relationship were observed for Asian, black, and white donors. These findings warrant further validation with more robust data to better inform clinical practice guidelines.