Simultaneous Surgeries Open Door to Kidney Transplants in Obesity

Pam Harrison

November 19, 2020

Severe obesity is often considered a relative contraindication to kidney transplant but now a pioneering simultaneous bariatric surgery plus kidney transplantation procedure, done robotically, gives hope to patients with morbid obesity plus end-stage renal failure.

"In the US, there is no clear-cut contraindication to kidney transplantation based on BMI but it's hard to find centers that are willing to do a kidney transplant in patients with a BMI above 35 kg/m2 because obese patients are at greater risk of surgical complications, particularly infections," the second author of the study, Pierpaolo Di Cocco, MD, assistant professor of surgery, University of Illinois at Chicago, explained to Medscape Medical News.

"Performing robotic-assisted weight loss surgery together with kidney transplant is the logical next step, addressing both renal failure and obesity at the same time. And the weight loss patients will experience from bariatric surgery should help improve comorbidities such as diabetes and hypertension, and this, in turn, could translate into longer function of the newly transplanted organ," Di Cocco elaborated. 

The study was published online November 9 in the American Journal of Transplantation by Mario Spaggiari, MD, also of the University of Illinois at Chicago, and colleagues.

Asked to comment, Perry Wilson, MD, said that a protocol like this has a good chance of expanding access to kidney transplantation in a population of patients who are often not considered eligible. 

"This is a good thing, though we must remember that kidneys for transplant are a limited resource — so this might be particularly useful among obese patients who have a potential living donor," Wilson suggested in an email. 

Wilson is a nephrologist and associate professor of medicine at Yale University School of Medicine in New Haven, Connecticut, and a contributor to Medscape Medical News.

Single-Center Study First to Prospectively Randomize Two Procedures

The single-center, prospective study involved 20 patients, 11 of whom were randomized to robotic-assisted sleeve gastrectomy (RSG) and robotic-assisted kidney transplantation (RAKT), and another nine patients underwent robotic-assisted kidney transplantation alone.

"To the best of our knowledge, this is the first prospective randomized controlled study combining a bariatric procedure with kidney transplant," the authors observe.

Mean BMI at the time of transplantation was very similar in both groups at around 44 kg/m2, as was mean duration of pretransplant dialysis, at between 2.5 and 3 years.

The time it took to complete the dual procedure was considerably longer, at 405 minutes, compared with 269 minutes for the kidney transplant alone (P = .003). The additional 2.3 hours of surgical time is consistent with previous reports of the time taken for robotic sleeve gastrectomy alone, the authors point out.

A higher rate of readmission within 30 days due to nausea and vomiting as well as acute kidney injury was seen among patients in the dual procedure group. To address this, patients had a peripherally inserted central catheter on day of discharge and had home intravenous fluid repletion with 2 L a day of crystalloid solution for the first month postoperatively.

A year after surgery, BMI dropped an average of 9 kg/m2 in the combined robotic sleeve gastrectomy and kidney transplant group, compared with an average gain of 2 kg/m2 in the transplant-only group (P = .004).

Patients in the dual-procedure group experienced an approximately 50% drop in excess weight, which is particularly noteworthy, as weight gain following transplantation is almost universal, the authors point out.

Estimated glomerular filtration rate, serum creatinine, readmission rates, and graft failure rates up to 12 months were not significantly different between the two groups.  

Robotic Approach Works Well for Kidney Transplant

The advantages of performing a kidney transplant using the robotic approach are striking, Di Cocco noted. "With the robot, we can perform very precise movements and do very fine sutures," he explained, which he says significantly reduces the risk of surgical complications.

But sleeve gastrectomy, though generally considered to be a safe procedure, can result in complications such as bleeding and leak, the authors note, although they didn't experience any such complications.

"[And while] the relatively short 1-year follow-up limits our ability to predict long-term graft function or, notably, secondary outcomes relating to the metabolic syndrome, our study shows that simultaneous robotic sleeve gastrectomy and kidney transplant is a safe and effective treatment modality for a selected population of patients with morbid obesity and end-stage renal disease," they conclude.

At the same time, however, they acknowledge that robotic-assisted surgery "is not broadly available."

Expanding Access for Patients With Obesity?

Wilson pointed out that the study doesn't answer the question of whether kidney transplant outcomes are significantly worse among those with obesity versus those without (as has been suggested by some studies) as all patients in the study had obesity. 

"As such, it's best viewed as a study that answers the question: If you are going to do a kidney transplant [in a patient with obesity], should a sleeve gastrectomy be done at the same time?" he said.

And he agreed with the authors that longer-term outcomes are needed to fully assess results.  

"However, these initial data seem to suggest that the kidney outcomes are similar, and the weight loss is substantially greater [with the dual procedure], which I would expect would increase the longevity of the kidney transplant."

"All in all, I'm happy to see surgical randomized controlled trials get the credit they deserve and this may advance a noble goal of making a kidney transplant available to every patient who needs one," Wilson emphasized. 

The authors and Wilson have reported no relevant financial relationships.

 Am J Transplant. Published online November 9, 2020. Abstract

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