Dynamic Frailty before Kidney Transplantation: Time of Measurement Matters

Background. Frail kidney transplant (KT) recipients have higher risk of adverse post-KT outcomes. Yet, there is interest in measuring frailty at KT evaluation and then using this information for post-KT risk stratification. Given long wait times for KT, frailty may improve or worsen between evaluation and KT. Patterns, predictors, and post-KT adverse outcomes associated with these changes are unclear. Methods. Five hundred sixty-nine adult KT candidates were enrolled in a cohort study of frailty (November 2009-September 2017) at evaluation and followed up at KT. Patterns of frailty transitions were categorized as follows: (1) binary state change (frail/nonfrail), (2) 3-category state change (frail/intermediate/nonfrail), and (3) raw score change (-5 to 5). Adjusted Cox proportional hazard and logistic regression models were used to test whether patterns of frailty transitions were associated with adverse post-KT outcomes. Results. Between evaluation and KT, 22.0% became more frail, while 24.4% became less frail. Black race (relative risk ratio, 1.98; 95% confidence interval [CI], 1.07-3.67) was associated with frail-To-nonfrail transition, and diabetes (relative risk ratio, 2.56; 95% CI, 1.22-5.39) was associated with remaining stably frail. Candidates who became more frail between 3-category states (hazard ratio, 2.27; 95% CI, 1.11-4.65) and frailty scores (hazard ratio, 2.36; 95% CI, 1.12-4.99) had increased risk of post-KT mortality and had higher odds of length of stay ≥2 weeks (3-category states: odds ratio, 2.02; 95% CI, 1.20-3.40; frailty scores: odds ratio, 1.92; 95% CI, 1.13-3.25). Conclusions. Almost half of KT candidates experienced change in frailty between evaluation and KT, and those transitions were associated with mortality and longer length of stay. Monitoring changes in frailty from evaluation to admission may improve post-KT risk stratification.