Diminishing significance of HLA matching in kidney transplantation

To determine trends in the significance of HLA matching and other risk factors in kidney transplantation, we analyzed data on graft survival in a consecutive sample of 33 443 transplant recipients who received deceased donor kidneys from December 1994 to December 1998 with a mean follow-up time of 2.2 years. HLA matching and other risk factors (peak panel reactive anti-body, donor age, sex and cause of death, cold ischemia time, donor and recipient body size) were examined. Mean likelihood ratios of models, fit with and without each variable of interest, were calculated by generating bootstrapped samples from each single year cohort. Pooled censored and uncensored graft survival rates were 90.6% and 89.9% at 1 year, 85.8% and 84.5% at 2 years, and 80.7% and 78.6% at 3 years. HLA matching declined in significance while other factors retained similar levels of statistical significance over the four yearly cohorts. With evolving clinical practice, including the provision of safer and more potent immunosuppressive therapy, the significance of HLA matching has diminished. Non-immunologic factors continue to impede more marked improvements in long-term graft survival. Recognizing these trends, organ allocation algorithms may need to be revised.