Impact of kidney transplantation in obese candidates: a time-dependent propensity score matching study

Background Although kidney transplantation (KT) is considered the best treatment for end-stage renal disease (ESRD), there are concerns about its benefit in the obese population because of the increased incidence of post-transplant adverse events. We compared patients who underwent KT versus patients awaiting KT on dialysis. Methods We estimated the life expectancy [restricted mean survival time (RMST)] for a 10-year follow-up by matching on time-dependent propensity scores. The primary outcome was time to death. Results In patients with a body mass index (BMI) >= 30 kg/m(2) (n = 2155 patients per arm), the RMST was 8.23 years [95% confidence interval (CI) 8.05-8.40] in the KT group versus 8.00 years (95% CI 7.82-8.18) in the awaiting KT group, a difference of 2.71 months (95% CI -0.19-5.63). In patients with a BMI >= 35 kg/m(2) (n = 212 patients per arm), we reported no significant difference [8.56 years (95% CI 7.96-9.08) versus 8.66 (95% CI 8.10-9.17)]. Hence we deduced that KT in patients with a BMI between 30 and 35 kg/m(2) was beneficial in terms of life expectancy. Conclusion Regarding the organ shortage, KT may be questionable for those with a BMI >= 35 kg/m(2). These results do not mean that a BMI >= 35 kg/m(2) should be a barrier to KT, but it should be accounted for in allocation systems to better assign grafts and maximize the overall life expectancy of ESRD patients.

Automated summary

This study compares the life expectancy of patients who underwent kidney transplantation (KT) versus patients awaiting KT on dialysis. The results suggest that KT is beneficial in terms of life expectancy for patients with a BMI between 30 and 35 kg/m(2). However, for patients with a BMI >= 35 kg/m(2), KT may be questionable and needs to be taken into consideration in organ allocation systems.