Obesity: An Independent Predictor of Morbidity and Graft Loss after Kidney Transplantation

BACKGROUND: There is conflicting information on current medical and surgical complications associated with high body mass index (BMI) after kidney transplantation. METHODS: In a single-center observational study, we analyzed the 5-year outcomes of all consecutive primary kidney transplant recipients between 2010 and 2015 based on BMI at the time of transplant. RESULTS: There were 1,467 patients included in this study, distributed in the following groups based on BMI: underweight (n = 32, 2.2%), normal (n = 407, 27.7%), overweight (n = 477, 32.5%), grade I obesity (n = 387, 26.4%), grade II obesity (n = 155, 10.6%), and grade III obesity (n = 9, 0.6%). Obesity was associated with an increased incidence of delayed graft function (p = 0.008), length of stay (LOS, p = 0.03), 30-day surgical re-exploration (p = 0.02), and hospital readmission (p < 0.0001). Obesity was also associated with higher 1-year serum creatinine (p = 0.03) and increased 5-year incidence of cardiac events (p < 0.0001) and congestive heart failure (p < 0.0001). Multivariable Cox regression analyses determined grade III obesity (HR = 5.84, 95% CI: 1.40-24.36, p = 0.01), LOS >4 days (HR = 1.94, 95% CI: 1.19-3.18, p = 0.008), hospital readmission (HR = 2.25, 95% CI: 1.20-4.22, p = 0.01), 1-year serum creatinine >1.5 (HR = 1.95, 95% CI: 1.20-3.18, p = 0.007), and proteinuria (UPC) >1 g/g (HR = 1.85, 95% CI: 1.06-3.24, p = 0.03) as independent predictors of death-censored graft failure. CONCLUSION: In the current era of renal transplant care, obesity is common, and high BMI remains associated with significant medical and surgical complications after transplant.