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

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.

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.

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).

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.