Impact of body mass index on graft loss in normal and overweight patients: retrospective analysis of 206 renal transplants

Abstract

Excess body mass is increasingly prevalent in transplant recipients. Currently, most investigators consider body mass index (BMI) a categorical variable, which assumes that all risk factors and transplant outcomes will be similar in all patients within the same category. We investigated the effect of categorical and continuous BMI increments on renal transplant outcome in normal weight (NW: BMI 18.5-24.9) and overweight (OW: BMI 25-30) patients. We retrospectively studied 206 patients. The mean BMI of our population was 24.3 ± 2.83 kg/m(2) . Patients of each group were similar regarding age, gender, time on dialysis, donor type, cold ischemia time, and number of HLA mismatches. The independent association of BMI with survival was determined using Cox multivariate regression. OW patients showed a higher prevalence of co-morbidities. In patients with graft loss, there was a higher incidence of delayed graft function, chronic allograft nephropathy, acute rejection, and hypertension. Graft survival was significantly lower in OW patients compared to NW patients upon Kaplan-Meier analysis (p = 0.008). In a multivariate Cox regression analysis, the initial BMI, evaluated as a continuous variable, remained an independent predictor of graft loss (hazard ratio 1.21, 95% CI 1.04-1.47). However, with patient stratification into World Health Organization BMI category and, further, into quartiles of initial BMI, no significant correlation between BMI category and graft loss was found. We suggest that increasing BMI value, although without categorical variation, may represent an independent risk factor for graft loss. Our retrospective analysis of a small sample population will require further studies to confirm these data.