The impact of waiting time and comorbid conditions on the survival benefit of kidney transplantation

Background. Longer waiting times may limit the survival benefit of kidney transplantation in older patients or those with a high burden of comorbid disease. Methods. We performed a longitudinal study of mortality among 63,783 transplant candidates who started dialysis between April 1995 and December 2000. We determined the relative risk (RR) of death and increase in life expectancy among subjects who received a first deceased donor transplant after different waiting times compared to subjects who had equivalent waiting times but remained on dialysis. Results. Transplant recipients had a lower long-term RR of death and the risk reduction was greatest in recipients with longer waiting times (RR of death 12 months after transplantation for recipients with waiting times of 0, 1, 2, 3 years was 0.49, 0.43, 0.38, 0.34, P= 0.0006).The average increase in life expectancy in transplant recipients was 9.8 years and was lower in older recipients and recipients with comorbid conditions. Increased waiting times from 1 to 3 years only moderately decreased the overall survival benefit of transplantation from 7.1 to 5.6 years, and all subjects derived a survival benefit from transplantation with waiting times up to 3 years. Conclusion. These findings do not support limiting access to transplantation for otherwise suitable candidates on the basis of longer anticipated waiting times.