Dear editors,

In their article “Towards adulthood with a solitary kidney” [1], in the section Long-term outcomes, the authors discuss the risk of end-stage renal disease (ESRD) in living kidney donors and cite data from two references [2, 3]. They state that “… the estimated risk of end-stage renal disease (ESRD) at 15 to 25 years after donation ranges between 8 and 11% compared to matched healthy non-donor counterparts” and note that the overall incidence of ESRD among donors was 302 cases per million. In the first study cited [2], 0.47% of the donors developed ESRD at a median time of 18.7 years after donation, and the overall incidence of ESRD was 0.03%. The risk of developing ESRD in the donors compared with controls was 11.38. In the second study [3], 0.1% of the donors developed ESRD at a mean time of 8.6 years after donation. The estimated cumulative incidence of ESRD at 15 years for donors was 0.31%, which was 7.8 times higher than the estimated cumulative incidence for controls. In the two studies, although the relative risk of ESRD in donors was 11 and 8 times the risk of matched controls, the cumulative incidence of ESRD at 15 years was less than 0.5%. These data do not support the authors’ conclusion that the risk of developing ESRD in living donors at 15–25 years after unilateral nephrectomy is 5 to 10% (question and answer 3b at the end of the paper).