Effect of the Obesity Epidemic on Kidney Transplantation: Obesity Is Independent of Diabetes as a Risk Factor for Adverse Renal Transplant Outcomes

Abstract

BackgroundObesity is a growing epidemic in most developed countries including the United States resulting in an increased number of obese patients with end-stage renal disease. A previous study has shown that obese patients with end-stage renal disease have a survival benefit with transplantation compared with dialysis. However, due to serious comorbidities, many centers place restrictions on the selection of obese patients for transplantation. Further, due to obese patients having an increased risk of diabetes, it is unclear whether obesity can be an independent risk, independent of diabetes for increasing adverse renal transplant outcomes.MethodsTo investigate the role of obesity in kidney transplantation, we used the Scientific Registry of Transplant Recipients database. After filtering for subjects that had the full set of covariates including age, gender, graft type, ethnicity, diabetes, peripheral vascular disease, dialysis time and time period of transplantation for our analysis, 191,091 subjects were included in the analyses. Using multivariate logistic regression analyses adjusted for covariates we determined whether obesity is an independent risk factor for adverse outcomes such as delayed graft function, acute rejection, urine protein and graft failure. Cox regression modeling was used to determine hazard ratios of graft failure.ResultsUsing multivariate model analyses, we found that obese patients have significantly increased risk of adverse transplant outcomes, including delayed graft function, graft failure, urine protein and acute rejection. Cox regression modeling hazard ratios showed that obesity also increased risk of graft failure. Life-table survival curves showed that obesity may be a risk factor independent of diabetes mellitus for a shorter time to graft failure.ConclusionsA key observation in our study is that the risks for adverse outcome of obesity are progressive with increasing body mass index. Furthermore, pre-obese overweight recipients compared with normal weight recipients also had increased risks of adverse outcomes related to kidney transplantation.

Obesity as a barrier to kidney transplantation: Time to eliminate the body weight bias?

“…7 Studies based on all US transplant recipient databases demonstrate an increased risk of, or shorter time to, graft failure with increasing BMI. [9][10][11] In those with a BMI >50 kg/m 2 , the risk of 30-day perioperative mortality, length of hospital stay, delay in graft function, and 1, 3 and 5 year mortality were all significantly greater than in any other BMI group. 13 Conversely, using data extracted from the UK Renal Registry and the National Health Service Blood and Transplant (NHSBT) database for the UK transplant recipient population, fully adjusted hazard ratios for graft survival and patient survival did not differ across BMI bands in transplanted patients, up to BMI >40kg/m 2 .…”

“…Recent systematic reviews on kidney transplant outcomes demonstrate an increased risk of delayed graft function with obesity 5-8 ; however, the data on mortality and graft survival are less clear. [5][6][7][8][9][10][11][12] The inconsistent conclusions appear to be related to methodological differences in inclusion criteria, date range, and statistical analyses.…”

“…Meta‐analyses indicate a small reduction in the unadjusted risk of graft failure in lower compared to higher BMI recipients (RR 0.97; 95% CI 0.96‐0.99) and a small increased risk of graft loss with higher BMI (adjusted HR 1.06; 95% CI 1.01‐1.12); yet in the seven studies using generalized linear modeling there was no difference in graft survival between low and high BMI (HR 1.00; 95% CI 0.96‐1.04) . Studies based on all US transplant recipient databases demonstrate an increased risk of, or shorter time to, graft failure with increasing BMI . In those with a BMI >50 kg/m 2 , the risk of 30‐day perioperative mortality, length of hospital stay, delay in graft function, and 1, 3 and 5 year mortality were all significantly greater than in any other BMI group …”

Clinical practice guidelines for the provision of renal service in Hong Kong: Potential Kidney Transplant Recipient Wait‐listing and Evaluation, Deceased Kidney Donor Evaluation, and Kidney Transplant Postoperative Care

“…In addition, there was no association demonstrated between obesity and either graft loss or death in studies of recipients who received a transplanted kidney after 2000 . Another analysis of 191 091 patients, from the Scientific Registry of Transplant Recipient database between the period 1987 to 2013, confirmed recipient obesity as independent risk factor for adverse outcomes, including delayed graft function, graft failure, proteinuria and acute rejection. In addition, a progressive increase in risk was linked with higher BMI categories.…”

“…In addition, a progressive increase in risk was linked with higher BMI categories. Another key observation was an increased risk even in pre‐obese overweight recipients with BMI 25–29.9 kg/m 2 compared to normal weight …”