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

Abstract

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. We estimated 5-year post-KT (n=151170; 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<-.07kg/m2 /month; stable [2nd quartile]: -.07 ≤ change ≤ .09kg/m2 /month; increase [3rd, 4th quartile]: change>.09kg/m2 /month) using adjusted Cox proportional hazards models. BMI increased in the 3years post-KT (.64kg/m2 /year, 95%CI: .63, .64) and decreased in years 3-5 (-.24kg/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≥30kg/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. BMI increases in the 3years 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.