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

Abstract

AbstractBackgroundEarly 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.MethodsWe 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 < −.07 kg/m2/month; stable [2nd quartile]: −.07 ≤ change ≤ .09 kg/m2/month; increase [3rd, 4th quartile]: change > .09 kg/m2/month) using adjusted Cox proportional hazards models.ResultsBMI 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.ConclusionsBMI 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.