Weight loss in renal transplant candidates does not improve post-transplantation outcome

Schold JD et al. (2007) A 'weight-listing' paradox for candidates of renal transplantation? Am J Transplant 7: 550–559

The belief that patients whose BMI is outside the normal range at the time of kidney transplantation have a poorer prognosis has led some centers to refuse to transplant obese patients and others to advise extreme pretransplantation weight loss. As weight loss is a risk factor for death in patients on dialysis, however, Schold et al. have investigated whether it should be recommended to patients scheduled to undergo kidney transplantation.

Data from 162,284 adults (aged 18–70 years) waitlisted for a first renal transplant in the US during the period 1990–2003 were analyzed; 124,713 patients received a transplant. Data obtained at time of placement on the waiting list, at time of transplantation, and up to 12 months after transplantation were used.

Underweight (BMI 13–20 kg/m²) and normal weight (BMI 20–25 kg/m²) kidney transplant candidates were at significantly higher risk of death during waitlisting relative to overweight (BMI 25–30 kg/m²) candidates (adjusted hazard ratios 1.42 and 1.11, respectively). Patients who were underweight, obese (BMI 30–35 kg/m²) or morbidly obese (≥35 kg/m²) at transplantation were at higher risk of death following surgery relative to overweight patients (adjusted hazard ratios 1.14, 1.08 and 1.28, respectively). When patients were stratified by baseline BMI, no relationship was found between absolute weight change (from waitlisting to transplantation) and graft loss or patient death after transplantation. In nonobese patients, rapid weight changes (increases or decreases) while awaiting transplantation were associated with higher risks of graft loss than were smaller changes.

The authors conclude there is no basis for indiscriminately encouraging overweight patients waitlisted for kidney transplantation to reduce their BMI.