Eligibility for the kidney transplant wait list: A model for conceptualizing patient risk

Background: Determining eligibility for a kidney transplant is one of the most important decisions facing nephrologists. It is assumed that the harm of kidney transplantation is minimal and most will benefit. The purpose of this study was to quantify the probability of 'no benefit' as defined by death on the wait list; 'harm', defined by the probability that a transplanted patient would live less than the average wait listed patient; and 'benefit' for the probability a transplanted patient would outlive the average wait listed patient. Methods: A computerized model was developed to replicate observed patient survival outcomes in deceased donor kidney transplantation. Three sequential periods of risk for the transplanted recipient compared to the wait listed cohort (increased, equivalent and reduced risk) were modeled. Results: The model predicted that wait listed patients with a baseline mortality of 28 deaths per 100 patient years were equally likely to benefit or be harmed with a transplant. However if 20% of patients on the wait list were on hold (assuming a 2.2-fold higher mortality than those who were transplanted), then the baseline mortality rate for equal harm or benefit decreases to 22 deaths per 100 patient years (equivalent life expectancy 4.5 years). Conclusion: Patients with limited life expectancies are more likely to suffer some harm than derive benefit from kidney transplantation.