Perfect timing, no remorse, and kidney transplantation.

Kidney transplantation is usually delayed until a patient has reached end-stage renal failure. When a living donor is used, earlier transplantation may be feasible. By averting the final stages of renal failure, early transplantation spares the patient the more pronounced effects of uremia. Unfortunately, lack of precision in predicting the future course of a patient's disease creates a dilemma: the kidneys could remain viable longer than anticipated. In that case, an early transplantation that leads to serious complications or graft failure will have caused harm by truncating the period of time the patient could have been sustained by his or her native kidneys. The present article introduces a theorem that helps solve the dilemma of early kidney transplantation. The theorem states that the timing decision depends only on the current burden of a disease relative to the risks of transplantation-that the future rate of progression of the disease is immaterial. The generality of the theorem makes it applicable, in principle, to any degenerative disease that can be treated by engraftment. The article also introduces a formula for the optimal timing of transplantation that depends on only four factors--a patient's perceived quality of life before transplantation as a function of time, the mortality associated with a transplant operation, the graft survival curve, and the quality of life in the event of a graft failure. The theorem and related formula should be helpful to patients and physicians in selecting the best time for transplantation.