Access to Kidney Transplantation in Adults With Severe Obesity: A Population-Based Retrospective Cohort Study

Abstract

Rationale & Objective International guidelines do not consider moderate or severe obesity to be a contraindication to kidney transplantation, but clinical practice suggests otherwise. This study evaluated the likelihood of kidney transplantation in patients with moderate or severe obesity and how that likelihood compared with patients with other risk factors. Study Design Retrospective population-based cohort study. Setting & Participants 96,181 adults with kidney failure, living in Canada between 2000 and 2021. Exposure Moderate or severe obesity and other risk factors (eg, age groups, diabetes, heart disease). Outcome Time to transplantation and time to allograft failure or death. Analytical Approach Parametric survival modeling, adjusting for all risk factors. Results Over a median follow-up period of 2.5 years, 58.2% of patients died, and 16.3% were transplanted. Participants with severe (body mass index [BMI] ≥ 40 kg/m2) or moderate (BMI 35.0-39.9 kg/m2) obesity were less likely to be transplanted than the control participants (BMI 18.5-24.9 kg/m2) (HR, 0.43 [95% CI, 0.39-0.47] and HR, 0.76 [95% CI, 0.71-0.82], respectively). Of 39 characteristics/categories considered, only participants aged ≥80 years were less likely to receive a transplant than those with severe obesity. Transplant recipients were followed for a median of 5.4 years. After those aged ≥65 years, participants with severe obesity were the most likely to experience allograft failure or death (HR, 1.70 [95% CI, 1.38-2.02] compared with controls). When we considered combinations of key risk factors, young participants with severe or moderate obesity and few comorbidities were at lower risk for allograft failure or death than participants with other common clinical characteristics. Limitations Residual confounding. Conclusions Canadian dialysis patients with moderate or severe obesity had a markedly reduced likelihood of receiving a kidney transplant. Although patients with moderate or severe obesity also had a heightened risk of allograft failure or death, the magnitude of the latter was similar to the excess risk associated with other common clinical characteristics. These findings support current practice guidelines and suggest that further work should identify and remove barriers to accessing kidney transplantation among patients with obesity. Plain-Language Summary International guidelines do not consider moderate or severe obesity (body mass index ≥35 and ≥40 kg/m2, respectively) to be a contraindication to kidney transplantation, but clinical practice suggests otherwise. Canadian dialysis patients with moderate or severe obesity had a reduced likelihood of receiving a kidney transplant (24% and 57%, respectively). Although patients with moderate or severe obesity also had a heightened risk of allograft failure or death (36% and 70%, respectively), the magnitude of the latter was similar to the excess risk associated with other common clinical characteristics that do not exclude a patient from kidney transplantation. These findings support current practice guidelines and suggest that further work should identify and remove barriers to accessing kidney transplantation among patients with moderate and severe obesity.