Post-kidney transplant body mass index trajectories are associated with graft loss and mortality

Abstract

Background: Early post-kidney transplantation (KT) changes in physiology, medications, and health stressors likely impact body mass index (BMI) and likely impact all-cause graft loss and mortality. Methods: We estimated 5-year post-KT (n = 151 170; SRTR) BMI trajectories using an adjusted mixed effects model. We estimated long-term mortality and graft loss risks by 1-year BMI change quartile (decrease [1st quartile]: change.09 kg/m2/month) using adjusted Cox proportional hazards models. Results: BMI increased in the 3 years post-KT (.64 kg/m2/year, 95% CI:.63,.64) and decreased in years 3–5 (−.24 kg/m2/year, 95% CI: −.26, −.22). 1-year post-KT BMI decrease was associated with elevated risks of all-cause mortality (aHR = 1.13, 95% CI: 1.10–1.16), all-cause graft loss (aHR = 1.13, 95% CI: 1.10–1.15), death-censored graft loss (aHR = 1.15, 95% CI: 1.11–1.19), and mortality with functioning graft (aHR = 1.11, 95% CI: 1.08–1.14). Among recipients with obesity (pre-KT BMI≥30 kg/m2), BMI increase was associated with higher all-cause mortality (aHR = 1.09, 95% CI: 1.05–1.14), all-cause graft loss (aHR = 1.05, 95% CI: 1.01–1.09), and mortality with functioning graft (aHR = 1.10, 95% CI: 1.05–1.15) risks, but not death-censored graft loss risks, relative to stable weight. Among individuals without obesity, BMI increase was associated with lower all-cause graft loss (aHR =.97, 95% CI:.95–.99) and death-censored graft loss (aHR =.93, 95% CI:.90–.96) risks, but not all-cause mortality or mortality with functioning graft risks. Conclusions: BMI increases in the 3 years post-KT, then decreases in years 3–5. BMI loss in all adult KT recipients and BMI gain in those with obesity should be carefully monitored post-KT.