Impact of obesity in kidney transplantation: a prospective cohort study from French registries between 2008 and 2014

Background: The access of obese patients to kidney transplantation is limited despite several studies showing that obese transplant recipients had a better survival rate than those undergoing dialysis. The aim of this study was to compare patient and graft survival rates and post-renal transplant complications in obese patients and non-obese patients and to assess the effect of pre-transplant weight loss in obese patients on transplant outcomes.

Methods: We carried out a prospective cohort study using two French registries, the Renal Epidemiology and Information Network and CRISTAL, on 7270 kidney transplant patients between 2008 and 2014 in France. We compared obese patients with non-obese patients and obese patients who lost more than 10% of weight before the transplant (obese WL and obese nWL).

Results: The mean BMI in our obese patients was 32 kg/m2. Graft survival was lower in obese patients than in non-obese patients {hazard ratio (HR) = 1.40, [95% confidence interval (95% CI) 1.09; 1.78], P = 0.007}, whereas patient survival was similar [HR = 0.94, (95% CI 0.73; 1.23), P = 0.66]. Graft survival was significantly lower in obese WL than in obese nWL [HR = 2.17, (1.02; 4.63), P = 0.045], whereas patient survival was similar in the two groups [HR = 0.79, (0.35; 1.77), P = 0.56].

Conclusion: Grade 1 obesity does not seem to be a risk factor for excess mortality after kidney transplantation and should not be an obstacle to having access to a graft. Weight loss before a kidney transplant in these patients should not be essential for registration on waiting list.