Pre‐Kidney Transplant Lower Extremity Impairment and Post‐Kidney Transplant Mortality

Prediction models for post‐kidney transplantation mortality have had limited success (C‐statistics ≤0.70). Adding objective measures of potentially modifiable factors may improve prediction and, consequently, kidney transplant (KT) survival through intervention. The Short Physical Performance Battery ( SPPB ) is an easily administered objective test of lower extremity function consisting of three parts (balance, walking speed, chair stands), each with scores of 0–4, for a composite score of 0–12, with higher scores indicating better function. SPPB performance and frailty (Fried frailty phenotype) were assessed at admission for KT in a prospective cohort of 719 KT recipients at Johns Hopkins Hospital (8/2009 to 6/2016) and University of Michigan (2/2013 to 12/2016). The independent associations between SPPB impairment ( SPPB composite score ≤10) and composite score with post‐KT mortality were tested using adjusted competing risks models treating graft failure as a competing risk. The 5‐year posttransplantation mortality for impaired recipients was 20.6% compared to 4.5% for unimpaired recipients (p < 0.001). Impaired recipients had a 2.30‐fold (adjusted hazard ratio [ aHR ] 2.30, 95% confidence interval [CI ] 1.12–4.74, p = 0.02) increased risk of post kidney transplantation mortality compared to unimpaired recipients. Each one‐point decrease in SPPB score was independently associated with a 1.19‐fold (95% CI 1.09–1.30, p < 0.001) higher risk of post‐ KT mortality. SPPB ‐derived lower extremity function is a potentially highly useful and modifiable objective measure for pre‐ KT risk prediction.