Background: Older patients constitute a growing proportion of U.S. kidney transplant recipients and often have a high burden of comorbidities. A summary measure of health such as functional status might enable transplant professionals to better evaluate and counsel these patients about their prognosis after transplant.
Methods: We linked United Network for Organ Sharing registry data about posttransplantation survival with pretransplantation functional status data (physical function [PF] scale of the Medical Outcomes Study Short Form-36) among individuals undergoing kidney transplant from June 1, 2000 to May 31, 2006. We examined the relationship between survival and functional status with multivariable Cox regression, adjusted for age. Using logistic regression models for 3-year survival, we also estimated the reduction in deaths in the hypothetical scenario that recipients with poor functional status in this cohort experienced modest improvements in function.
Results: The cohort comprised 10,875 kidney transplant recipients with a mean age of 50 years; 14% were ≥65. Differences in 3-year mortality between highest and lowest PF groups ranged from 3% among recipients <35 years to 14% among recipients ≥65 years. In multivariable Cox regression, worse PF was associated with higher mortality (hazard ratio, 1.66 for lowest vs. highest PF quartiles; P<0.001). Interactions between PF and age were nonsignificant. We estimated that 11% fewer deaths would occur if kidney transplant recipients with the lowest functional status experienced modest improvements in function.
Conclusions: Across a wide age range, functional status was an independent predictor of posttransplantation survival. Functional status assessment may be a useful tool with which to counsel patients about posttransplantation outcomes.