The Penalty of Being Obese: An Evaluation of the BMI Threshold Criterion for Transplantat

This paper examines the effects of a weight loss intervention for End State Renal Disease (ESRD) patients on the waiting list for kidney transplantation. Various transplant centers have instated a BMI eligibility requirement for listing and/or transplantation with a BMI threshold of BMI≥35kg/m² (Class II & III obesity).  The BMI eligibility criterion provides an incentive for transplant candidates to become healthier. This requirement could lead to improved patients’ health outcomes, especially transplant outcomes, by reducing obesity-related hazards. Nonetheless, it serves as a demand curbing mechanism and limits access to transplantation for Class II & III obese ESRD patients by making it more difficult for obese candidates to be listed and obtain transplantation.

First, we analyze the impact of individual BMI classification at listing on transitions from the waiting list. Using a hazard model analyzing time to events (i.e. time to transplantation, death, and removal for all other causes) with a semi-parametric approach we find that obesity has a negative effect on the likelihood of transplantation. The penalty for Class II & III obesity, as a result of the BMI eligibility requirements, is estimated at 17.26 percentage points for deceased donor transplant and 17.29 percentage points for living donor transplant relative to the lowest level of obesity (30≤BMI<35). We further investigate the effectiveness of this intervention in a regression-adjusted difference in difference framework on a sample of cadaveric donor transplant recipients and find that the probability of sustainable weight loss increases by about 10 percentage points for deceased donor transplant recipients in general at centers with a threshold. However, results suggest weak evidence that Class II & III obese candidates respond to the incentive of transplantation. The intervention does not seem to affect graft failure rates for patients who experience sustainable weight loss and there is little effect on labor force participation at transplant for this group.