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BALTIMORE -- An advisory panel for the Centers for Medicare and Medicaid Services meeting Wednesday could not agree that coverage of bariatric surgery should be expanded in the Medicare population.

With an average vote of 2.08 (scale of 1-5 for confidence, with 1 being the lowest) by the 13 voting-member Medicare Evidence Development & Coverage Advisory Committee (MedCAC), most but not all indicated that the current literature was not robust enough to assess the long-term benefit/risk balance for bariatric surgery in obese Medicare beneficiaries.

Although Medicare currently covers some bariatric procedures -- including open and laparoscopic Roux-en-Y gastric bypass, open and laparoscopic biliopancreatic diversion with duodenal Switch, gastric reduction Duodenal Switch, and laparoscopic gastric banding -- such coverage comes with restrictions and conditions. Coverage is available only to beneficiaries with morbid obesity (BMI≥35), those with a minimum of one obesity-related comorbid condition, such as type 2 diabetes, and those that have previously attempted another medical treatment for obesity.

"In the Medicare-age population -- traditional Medicare age population -- there is a lack of evidence in that population, but I thought [a vote of] 4 was applicable only because the average age of overall Medicare population is easily represented by the surrogate data from younger patients out of Medicare. In particular, I thought the type of procedure, gender, age, and collective markers for metabolic syndrome were all very predictive," said panel member Adolph J. Yates, Jr., MD, of the University of Pittsburgh School of Medicine, citing earlier data presented earlier in the daylong meeting.

Diana Zuckerman, PhD, president of the National Center for Health Research, responded, "I voted 1 [no confidence] because I thought that it wasn't clear how well we could predict benefit among the Medicare population, and especially the disabled, because I did not make the assumption that Medicare patients who are on Medicare because of disability are similar to non-Medicare patients of the same age range. I just felt we had no data to say that was true or not true."

Panel member Bruce M. Wolfe, MD, of Oregon Health & Science University, said the panelists' lack of consensus may in part be due to the fact that the definition of "success" is likely to vary from provider to patient.

However, the panel was confident that weight loss following bariatric surgery was an important outcome measure for determining whether Medicare should provide coverage, with an average vote of 4.77. The panel also concluded they felt confident that postoperative complications were also an important outcome of bariatric surgery for recommending whether Medicare should pay (4.69).

Outcomes of comorbidities with bariatric surgery were also a hot topic of discussion throughout the day's discussions, especially regarding diabetes and metabolic outcomes, which received a similarly confident vote of 4.77 for being important in decision-making.

However, Aloysius B. Cuyjet, MD, MPH, acting committee chair of the panel, said the duration of anti-diabetic effect remained to be determined, and more long-term studies are needed to clarify it as well as subgroups most likely to benefit.

"That's a pertinent issue because what should the endpoint be regarding diabetes," replied Wolfe. "Is it remission? Is it better control? Is it long-term complications? Is it survival? It could be any of those, but certainly the STAMPEDE Trial, which is probably the most celebrated -- the endpoint is A1c, not remission, because the entry criteria was absolutely uncontrolled diabetes. If that's your population, then the remission rate will be low. Whereas in the LABS 3 Diabetes Trial, insulin was an exclusion, so remission rate was 92%. So it depends a great deal on what's the entry criteria."

The panel also felt generally confident that the following should be considered primary health outcomes to evaluate the benefits of bariatric intervention, including:

• Cardiovascular outcomes: 4.23
• Quality of life: 4.15
• Respiratory outcomes: 3.46
• Musculoskeletal outcomes: 3.46

Short-term outcomes of 2 years or less following surgery were thought to have proven the benefits outweigh the associated harms, the panel felt, with an average vote of 3.69. The panel was less certain about the benefits from 2-5 years, with an average vote of 3.15, and averaged 2.77 on the question of risks versus benefits for outcomes beyond five years.

Cuyjet suggested that future research on bariatric surgery including the Medicare population needs to be "very inclusive in the populations that are enrolled in the studies."

"We need to make a real effort to try and understand the treatment differences among different populations at risk," he suggested. Several of the other panel members also noted that subgroup analyses are key in future studies, so as to not hide differences in outcomes and benefit/risk profiles of various populations.

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