NATIONAL HARBOR, MD. – A standard definition of bariatric surgery failure based on weight regain is needed to assess long-term outcomes in place of the seemingly arbitrary thresholds now in use, according to discussion generated by long-term outcome studies presented at Obesity Week 2017.

In one of two studies evaluating weight recidivism in long-term follow-up after bariatric surgery, failure rates at 10 years ranged from 25% to more than 70% according to the definition used, reported to Michael C. Morell, MD, a bariatric surgeon at the Gundersen Medical Foundation, Encinitas, CA.

In another study, presented by Colin Martyn, MD, a general surgery resident at Texas Tech University Health Sciences Center, El Paso, the bariatric surgery failure rate at 11 years was characterized as an “alarming” 33.9%. In this study, bariatric surgery was considered a failure if the patient did not maintain excess weight loss (EWL) of 50% or greater.

The problem with this definition, like many others, is that “it fails to recognize that there could be significant health benefits and improvements in quality of life with less weight loss,” according to Philip Schauer, MD, director of the Cleveland Clinic Bariatric and Metabolic Institute. As the invited discussant for the data presented by Dr. Martyn, Dr. Schauer acknowledged that 50% EWL has been used by others as the dividing line between success and failure, but he called it “obsolete.”

This definition was one of several applied to weight recidivism in the study presented by Dr. Morell. Others included weight regain of more than 25% EWL over the postoperative nadir, an increase in body mass index to more than 35 kg/m² after achieving a lower BMI, and a postsurgical BMI increase of more than 5 mg/m². Not surprisingly, weight recidivism “varied widely with regard to the definitions used,” Dr. Morell reported.

Dr. Morell’s study involved evaluation of 1,766 patients with at least 1 year of follow-up after bariatric procedure. Most (1,490 patients) underwent laparoscopic Roux-en-y gastric bypass. After 2 years of follow-up, 93% achieved at least the 50% EWL threshold of treatment success, but Dr. Morell reported that the proportion above this or any threshold progressively diminished over time. For a definition of treatment success, Dr. Morell favors maintenance of at least 20% total weight loss as a threshold of long-term clinical success, a threshold met by 75% of patients at 5 years, in his analysis.

In the meta-analysis presented by Dr. Martyn, nine published studies with at least 7 years of follow-up were included. These involved a cumulative 345 patients followed for at least 7 years with diminishing numbers followed up to 11 years. Using the at least 50% EWL as the definition of treatment success, the overall failure rate was 27.8% at 7 years but climbed to 33.9% at 11 years.

As has been shown in these studies and reported previously, the regaining of weight over time after bariatric surgery is common and progressive, but both studies ignited controversy about what measure is meaningful for declaring that bariatric surgery has failed over the long term. None of the current thresholds for failure are based on evidence that clinical benefit has been lost. Rather, it appears that these are simply accepted conventions.

“It bothers me to hear the word failure in these presentations, because I think the paradigm is changing from success and failure to that of treating chronic disease,” said Stacy Brethauer, MD, a staff surgeon in the Cleveland Clinic Digestive Disease Institute. Dr. Brethauer, the moderator of the session at Obesity Week where both long-term follow-up papers were presented, agreed that the at least 50% EWL benchmark is “flawed.” He suggested that more clinically meaningful methods of evaluating long-term outcome are needed for both clinical and research purposes.

The discussant of Dr. Morell’s paper, Samer G. Mattar, MD, a bariatric surgeon at the Swedish Medical Center, Seattle, also called for metrics based on clinical benefit rather than on weight alone.

“I would caution against this overall emphasis that we seem to place on weight gain and weight loss as a benchmark and predominant objective for what we do,” he said. “Our nonsurgeon colleagues have repeatedly demonstrated clinical benefits from total body weight loss of 10% or even 5%. So let’s not beat up ourselves over trying to maintain a greater than 50% EWL in all our patients.”

cenews@frontlinemedcom.com

Weight recidivism after bariatric surgery: What constitutes failure?