Functional Status and Survival After Kidney Transplantation

Abstract

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 UNOS registry data about post-transplant survival with pre-transplant functional status data (physical function [PF] scale of the Medical Outcomes Study Short Form-36) among individuals undergoing kidney transplant from 6/1/2000 – 5/31/2006. We examined the relationship between survival and functional status with multivariable Cox regression, adjusted for age. Using logistic regression models for three-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 (KTRs) with a mean age of 50 years; 14% were ≥65. Differences in three-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 (HR 1.66 for lowest versus highest PF quartiles; p<0.001). Interactions between PF and age were non-significant. We estimated that 11% fewer deaths would occur if KTRs with the lowest functional status experienced modest improvements in function. Conclusions Across a wide age range, functional status was an independent predictor of post-transplant survival. Functional status assessment may be a useful tool with which to counsel patients about post-transplant outcomes.

Relationship between pre-transplant physical function and outcomes after kidney transplant

“…For example, Kutner et al found that lower physical function scores on the Kidney Disease Quality of Life-Short Form instrument were associated with hospitalization/death after kidney transplant [31]. Similarly, Reese et al found that lower physical function scores on the SF36 were associated with shorter 3-year survival following kidney transplant [32, 33]. In addition to these studies utilizing self-reported measures of physical function, other studies have examined the relationship between pre-transplant frailty and post-transplant outcomes.…”

Functional Status, Time to Transplantation, and Survival Benefit of Kidney Transplantation Among Wait-Listed Candidates

“…7 Complementary studies that have examined functional status as well as frailty among kidney transplant recipients suggest that post-transplantation complications such as early rehospitalization will also be more common among patients with worse global health. 6 …”

“…We excluded individuals who were never active on the wait-list, or wait-listed for multi-organ transplants other than kidney-pancreas. 7 The observation period was June 1 2000 until September 3 2010.…”

“…Using national cohorts, Kutner et al and Reese et al demonstrated that functional status, measured using the physical function (PF) domain of the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), was strongly associated with post-transplantation survival. 6,7 The SF-36 instrument is usually self-administered and has been implemented in diverse populations, including dialysis patients and individuals without kidney disease. 8-10 Frailty, a syndrome of vulnerability to medical stressors, is also common among kidney transplant recipients and was reported to be associated with delayed graft function, early rehospitalization, and mortality in a single center cohort.…”

Report from the American Society of Transplantation on frailty in solid organ transplantation

“…A large, multicenter study of frailty among kidney transplant candidates (n = 3938; enrolled at the time of evaluation) and kidney transplant recipients (n = 1291; enrolled at admission) is currently ongoing. Using the Medical Outcomes Study Short Form-36 (SF-36) Physical Component Scale (PCS) questionnaire to evaluate physical function, analysis of the United Network for Organ Sharing (UNOS) registry data of 10 875 kidney transplant recipients identified low physical function as an independent predictor of mortality (HR = 1.7) 41. 32 Additionally, in this large cohort, McAdams-DeMarco and colleagues found that frailty at the time of kidney transplant evaluation was associated with a 2.8-fold higher odds of fair or poor healthrelated quality of life (HRQOL) and a 2.9-fold higher risk of declining HRQOL while waiting for kidney transplantation 33 and 2.2-fold increased risk of waitlist mortality.…”