Moving closer to understanding the risks of living kidney donation.

Recent studies from the United States and Norway have suggested an unexpected 8- to 11-fold relative risk of ESRD after kidney donation, but a low long-term absolute risk. Abundant renal epidemiologic data predict that these studies have underestimated long-term risk. The 1% lifetime post-donation risk in the US study requires medical screening to predict ESRD in 96 of 100 candidates. This is particularly unlikely in the 30-35% of candidates under age 35, half of whose lifetime ESRD will occur after age 64. Many experts have attributed the increased relative risks in these studies to loss of GFR at donation, which ultimately means that high-normal pre-donation GFRs will reduce absolute post-donation risks. The 8- to 11-fold relative risks predict implausible risks of uninephrectomy in the general population, but lower estimates still result in very high risks for black donors. Young vs. older age, low vs. high-normal pre-donation GFRs, black race, and an increased relative risk of donation all predict highly variable individual risks, not a single "low" or "1%" risk as these studies suggest. A uniform, ethically defensible donor selection protocol would accept older donors with many minor medical abnormalities but protect from donation many currently acceptable younger, black, and/or low GFR candidates.