Size does matter-donor-to-recipient body mass index difference may affect renal graft outcome

Background: Obesity, in the either kidney donor or the recipient, has been related to worse graft function. The aim of this study was to compare long-term graft outcomes of living-related kidney recipients regarding the donor-to-recipient body mass index (BMI) ratio. Methods: From November 2002 to November 2010, 62 consecutive living-related kidney transplantations were performed at our center. Donor and recipient BMIs were categorized by Taiwan's national standard using dividing values of 18.5, 24, and 27 kg/m ² to divide subjects into donor-to-recipient BMI categories. These with the same BMI category as their donors were defined as the same-BMI group (group 0); recipients with a lower BMI category than their donors were defined as the large-to-small group (group 1); and those with a higher BMI category than their donors were defined as the small-to-large group (group 2). Baseline parameters and posttransplantation follow-up data were analyzed according to this grouping. Results: Of the 57 recipients followed regularly at our hospital (mean follow-up 48.9 months), 21 (36.8.1%) were in group 0; 26 (45.6%) in group 1, and 10 (17.6%) in group 2. The baseline parameters were similar among these groups. The overall graft survival rates were 81.0% in group 0, 76.9% in group 1, and 90.0% in group 2. The rejection-free graft survival rates were 81.0%, 65.4%, and 90.0%, respectively. By Kaplan-Meier analysis, group 1 showed worse rejection-free graft survival than group 0 or group 2 (log-rank P =.046). Conclusions: Living-related recipients of kidneys from donors with a higher BMI showed lower long-term graft survival, which might suggest that petite recipients may need time to compensate adequate blood flow for the relative large graft, thus carrying a higher chance of rejection and worse graft outcomes.