Use of BMI requirement pre-transplant remains controversial
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Setting an acceptable BMI range for a potential kidney transplant recipient remains a controversial topic within the transplant community, sources told Healio/Nephrology News & Issues.
“It is a contentious issue,” Beatrice Concepcion, MD, medical director of the kidney transplant program at the University of Chicago, told Healio/Nephrology News & Issues. “In general, for recipients, transplant centers may look at a BMI of 40 [kg/m2] as a cutoff, and up to 45 [kg/m2] in select cases.
“Some centers that do robotic surgery are able to transplant at higher BMIs,” she said.
Most of the concerns regarding a high BMI in transplant recipients “have to do with complications post-op (eg, wound infection/healing) and inferior longer-term cardiovascular outcomes,” Concepcion, an Associate Editor for Healio/Nephrology News & Issues, said.
Candidates for kidney transplant already on the waitlist may be passed over in obtaining a donor kidney because of their weight. A prospective analysis by Dorry L. Segev, MD, PhD, and colleagues of 132,353 patients who were registered for kidney transplantation in the United States between 1995 and 2006 showed the likelihood of receiving a transplant “decreased with increasing degree of obesity, categorized by ranges of BMI compared with a reference group of patients with normal BMI.
“Similarly, the likelihood of being bypassed when an organ became available increased in a graded manner with category of obesity,” Segev and colleagues wrote in the Journal of the American Society of Nephrology. “Although matching an available organ with an appropriate recipient requires clinical judgment, which could not be fully captured in this study, the observed differences are dramatic and warrant further studies to understand this effect better and to design a system that is less susceptible to unintended bias.”
Segev, who wrote the paper in 2008 and is now a professor of surgery and population health member at the National Academy of Medicine and vice chair for research in the department of surgery and director of the Center for Surgical and Transplant Applied Research at NYU Langone Health, told Healio/Nephrology News & Issues he believes transplant centers are still reluctant to accept prospective transplant recipients who are obese, but “more centers are offering patients bariatric surgery to improve transplant eligibility and reduce reluctance to transplant, and a small handful are doing robotic recipient operations to reduce the wound complications associated with obesity,” he said.
Complications
In an article published in BMC Nephrology, Uwe Scheuermann, MD, and colleagues from the department of visceral, transplantation, vascular and thoracic surgery at the University Hospital of Leipzig in Germany reviewed the outcomes of 578 patients who received a kidney transplant between 1993 and 2017. Normal weight (BMI 18.5 – 24.9 kg/m2; n=304), overweight (BMI 25 – 29.9 kg/m2; n=205) and obese (BMI30 kg/m2; n=69) groups were established.
“Obesity was associated with an increased rate of surgical complications, such as wound infection, fascial dehiscence and lymphoceles,” Scheuermann and colleagues wrote. “Furthermore, the hospital stay duration was significantly longer in the groups with obese patients compared to normal weight and overweight patients (normal weight: 22 days, overweight: 25 days, and obese: 33 days), respectively,” they wrote.
A multivariate analysis showed that obesity was an independent prognostic factor for delayed graft function and postoperative surgical complications.
In a study published in the Journal of Clinical Medicine, Renana Yemini, MD, and colleagues compared the post-transplant risk for obese patients with a BMI greater than 30 kg/m2 vs. nonobese patients. They also compared the two groups based on whether patients received a living donor (LD) vs. a deceased donor (DD) graft. “The results demonstrated that the risk for graft loss and death were significantly higher among the patients with obesity,” the authors wrote. “When analyzing the results according to graft type, LD vs. DD, a high BMI was also associated with significantly increased mortality in both subgroups of graft sources. However, when comparing graft survival between BMI groups in the LD and DD transplant, the difference was seen in the DD group but not in the LD group.”
Guidelines
In 2020, guidelines published by a Kidney Disease: Improving Global Outcomes (KDIGO) work group said patients should not be turned down for a kidney transplant because of obesity. However, the work group did acknowledge the risks that obesity presents post-transplant.
“The impact of obesity on kidney transplant outcomes is complex,” work group members wrote. “When compared to remaining on dialysis, obese patients who undergo kidney transplant experience prolonged survival,” citing recent research demonstrating a 48% reduction in mortality after transplantation compared with remaining on dialysis. However, “a recent meta-analysis including more than 200,000 recipients comparing outcomes in obese and nonobese recipients, demonstrated that obesity (BMI >30 kg/m2) conveys an increased risk of death, delayed graft function, acute rejection, wound infection, dehiscence and prolonged hospital stay (2.31 days),” they wrote.
“Consequently, the work group recommends assessment of all candidates for obesity using either BMI or waist to-hip criteria ... Patients found to be obese or particularly those with class II or class III obesity (BMI 35 kg/m2) should be considered for intervention, such as dietary counseling or bariatric surgery.”
- References:
- Kidney Disease: Improving Global Outcomes (KDIGO) Kidney Transplant Candidate Work Group. KDIGO clinical practice guideline on the evaluation and management of candidates for kidney transplantation. Transplantation. 2020;104: S1–S103.
- Scheuermann U, et al. BMC Neph. 2022;doi:10.1186/s12882-022-02668-z.
- Segev D, et al. J Am Soc Nephrol. 2008;doi:10.1681/ASN.2007050610.
- Yemini R, et al. Jrnl of Clin Med. 2022;doi:10.3390/jcm11113069.
- For more information:
- Beatrice Concepcion, MD, can be reached at beatrice.p.concepcion@vumc.org.
- Dorry L. Segev, MD, PhD, can be reached at dorry.segev@ nyulangone.org.
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