Intermediate Renal Outcomes, Kidney Failure, and Mortality in Obese Kidney Donors

Abstract

Significance Statement Obesity’s association with diabetes, hypertension, and possibly kidney disease has prompted concerns that these effects might be magnified after kidney donation in the donor’s remaining kidney. Half of US transplant centers exclude donation from kidney donor candidates who are obese. This comparison of mortality, kidney failure, proteinuria, diabetes, and hypertension in 6822 nonobese donors and 1761 obese donors showed that obesity in kidney donors, as in the general population, is associated with increased risk of developing diabetes, hypertension, and proteinuria. Mortality was similar between obese and nonobese donors. Absolute risk of ESKD was 0.5% in nonobese donors, 0.7% in obese donors, and 0.9% in very obese donors (body mass index <30 kg/m 2 , ≥30 kg/m 2 , or >35 kg/m 2 , respectively). Judicious acceptance of obese but otherwise healthy donor candidates should be considered. Background Obesity is associated with the two archetypal kidney disease risk factors: hypertension and diabetes. Concerns that the effects of diabetes and hypertension in obese kidney donors might be magnified in their remaining kidney have led to the exclusion of many obese candidates from kidney donation. Methods We compared mortality, diabetes, hypertension, proteinuria, reduced eGFR and its trajectory, and the development of kidney failure in 8583 kidney donors, according to body mass index (BMI). The study included 6822 individuals with a BMI of <30 kg/m 2 , 1338 with a BMI of 30–34.9 kg/m 2 , and 423 with a BMI of ≥35 kg/m 2 . We used Cox regression models, adjusting for baseline covariates only, and models adjusting for postdonation diabetes, hypertension, and kidney failure as time-varying covariates. Results Obese donors were more likely than nonobese donors to develop diabetes, hypertension, and proteinuria. The increase in eGFR in obese versus nonobese donors was significantly higher in the first 10 years (3.5 ml/min per 1.73m 2 per year versus 2.4 ml/min per 1.73m 2 per year; P <0.001), but comparable thereafter. At a mean±SD follow-up of 19.3±10.3 years after donation, 31 (0.5%) nonobese and 12 (0.7%) obese donors developed ESKD. Of the 12 patients with ESKD in obese donors, 10 occurred in 1445 White donors who were related to the recipient (0.9%). Risk of death in obese donors was not significantly increased compared with nonobese donors. Conclusions Obesity in kidney donors, as in nondonors, is associated with increased risk of developing diabetes and hypertension. The absolute risk of ESKD is small and the risk of death is comparable to that of nonobese donors.

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