Bariatric surgery for diabetes gaining ground: many experts believe bariatric surgery is appropriate for patients with inadequately controlled diabetes.
Since 1991, when the National Institutes of Health's (NIH) guidelines recommended that bariatric surgery be considered for patients whose body mass index (BMI) is greater than 40 kg/[m.sup.2]--or greater than 35 in those with coexisting illnesses such as diabetes--major advances have taken place in surgical experience, techniques, and outcomes. According to data from the Agency for Healthcare Research and Quality, between 1998 and 2004 there was a 79% reduction in the mortality rate during hospitalization following bariatric surgery, Dr. Bruce Wolfe said at a congress on interventional therapies for type 2 diabetes.
And 12-month data from the American Society for Metabolic and Bariatric Surgery (ASMBS) now show that after 66,000 procedures, the 30-day mortality rate is 0.3%, the readmission rate is 5%, and the rate of reoperations is 2.4%, said Dr. Wolfe, who is professor of surgery at Oregon Health and Science University, Portland.
There have now been eight published studies of various types of bariatric surgery that included some type of comparator group, all showing reductions in mortality ranging from 29% to 88%, according to Dr. Ted Adams of the University of Utah, Salt Lake City. These trials have also demonstrated multiple other benefits, such as improvements in diabetes symptoms and hypertension.
Surgery is increasingly being done for diabetic patients whose BMIs are in the 30s, but conflict exists as to whether the evidence is sufficient to specifically recommend bariatric surgery for these patients, given the fact that early deaths still occur and uncertainty remains regarding late complications.
Some experts believe the evidence is not yet in. "We need to follow these patients not for 30 days or a year, but for 10-15 years," said Dr. Xavier Pi-Sunyer, professor of medicine, Columbia University Medical Center, and chief, division of endocrinology, diabetes, and nutrition, St. Luke's--Roosevelt Hospital Center, both in New York.
"We are seeing a lot of complications now in patients who had their surgery 2 or 3 years ago--bone problems, anemia, nutritional abnormalities, and hypoglycemia," Dr. Pi-Sunyer said.
A safety concern that has been gaining attention is the late development of post-prandial hypoglycemia and nesidioblastosis after gastric bypass. Although this is not common, it is potentially troublesome. Patients have experienced significant hypoglycemia that resulted in seizures and even automobile accidents, and about 100 patients have had to undergo pancreatectomy, according to Dr. Allison Goldfine of Harvard Medical School and head of the clinical research section, Joslin Diabetes Center, both in Boston.
Moreover, medical therapy today is successful in many patients, with 55% of patients being able to achieve a hemoglobin [A.sub.1c] of 7% or less, according to Dr. Richard Hellman of the University of Missouri-Kansas City.
"We need to have a lot more data, which can only be obtained by doing a carefully controlled randomized study of sufficient length, perhaps 5 years or more, and see if there are subsets of patients who have different risk-benefit ratios," said Dr. Hellman, who is also past president of the American Association of Clinical Endocrinologists and chancellor of the American College of Endocrinology.
The surgeons are more enthusiastic. "I don't have any doubt that patients with BMIs of 40 and 50 have much to gain from surgery, to which there is a 90% good response," said Dr. Mario Morino, professor of general surgery, University of Turin (Italy). "At my center we have a yearlong waiting list."
Considerable practical obstacles further complicate the disagreement as to whether indications for surgery should be expanded in type 2 diabetes to those with lower BMIs or whether a randomized trial must first be done. For one thing, costs could exceed $100 million, according to Dr. John Buse, who is professor of medicine and chief of the division of endocrinology, University of North Carolina at Chapel Hill.
In addition, Dr. Wolfe noted that when the NIH bariatric surgery consortium was last convened, participants spent a year discussing whether a randomized trial of weight loss surgery should be undertaken, and they concluded that such a trial was not feasible, appropriate, or even necessary.
The Rome Conference
All of these concerns were aired during a conference in Rome in 2007 that centered on reviewing the available evidence, identifying indications and contraindications, and beginning to establish regulatory and scientific oversight for bariatric surgery, specifically for type 2 diabetes.
Attending the Rome conference were authorities on diabetes, obesity, and bariatric surgery, with 52 voting faculty. The numbers were weighted toward nonsurgeons to avoid potential conflicts of interest, according to Dr. David Cummings of the division of metabolism, endocrinology, and nutrition, and deputy director of the diabetes endocrinology research unit, at the University of Washington, Seattle.
From the Rome conference emerged a document containing a number of consensus statements, with consensus being defined as agreement by a two-thirds majority. Dr. Cummings described these statements and the questions posed to elicit them.
"First we asked the question, reiterating the 1991 [NIH guidelines] statement, 'Should gastrointestinal surgery be considered for patients with type 2 diabetes who are appropriate surgical candidates with BMIs over 35 who are inadequately controlled on medical therapy?' and there was 100% agreement" that the answer was yes, Dr. Cummings said.
"We then considered whether it was reasonable, based on available information, to begin exploring the use of any type of gastrointestinal surgery in patients with lower BMIs and diabetes," he said. To the question of whether this would be appropriate for inadequately controlled patients with BMIs between 30 and 35, 82% agreed.
More specifically, the question was then asked whether gastric bypass might be appropriate in this patient group, and 73% agreed. "This may be the most far-reaching item that we had a solid consensus on," Dr. Cummings said.
Consensus was not reached on the use of other procedures, such as biliopancreatic diversion, duodenal switch, and sleeve gastrectomy.
"We also had a number of general statements about the importance of research and collaboration among surgeons, nonsurgeons, and policy makers, and that new procedures should only be conducted in the context of clinical trials with [institutional review board] approval," Dr. Cummings said.
Following the presentation of the Rome consensus document to the world congress participants, Dr. Philip Schauer, who is professor of surgery at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University and director of the Cleveland Clinic Bariatric and Metabolic Institute, asked for comments and endorsement from representatives of various interested organizations.
Speaking on behalf of the Obesity Society was Dr. Caroline Apovian of Boston University.
"We are still in the process of reviewing the document, but the response so far has been very positive," she said. "We would like to see more long-term data, but I'm positive we will be able to endorse it," she said.
Representing the American Association of Clinical Endocrinologists was Dr. Jeffrey Mechanick of the division of endocrinology, diabetes, and bone disease and director of metabolic support, Mount Sinai School of Medicine, New York.
"We enthusiastically endorse all the elements of the document relating to research, and to collaborative efforts to advance the knowledge for surgical intervention in type 2 diabetes," Dr. Mechanick said.
"However, anything outside the framework of research we as a society are unable to endorse at the present time, primarily because of the lack of sufficient long-term data on benefits and, particularly, the risks of surgery specifically for diabetes," he said.
"We can draw a parallel with osteoporosis, where for a long time the only show in town was the T score, but now we have access to FRAX [Fracture Risk Assessment Tool] data and are coming up with risk factor scores for therapeutic decision making. We need to establish a risk stratification system in type 2 diabetes and not just rely on a biomarker such as [Hb][A.sub.1c]," Dr. Mechanick said.
Speaking for the American Diabetes Association (ADA) was the organization's vice president of clinical affairs, Dr. Sue Kirkman, who expressed concerns about the "straw poll" two-thirds majority procedures followed in the Rome conference. The ADA may assemble its own consensus conference, following an iterative process wherein the language of each statement is refined so everyone can agree, she said.
"We try to be evidence-based, and many times what you think is true doesn't turn out to be true," Dr. Kirkman said. "For a long time the ADA was criticized for not saying that if people controlled their glucose they would have reduced cardiovascular disease, based on observational evidence. Then three recent randomized trials came out showing that tight glucose control didn't reduce cardiovascular disease after all," she said.
A different view was expressed by Dr. Scott Shikora, who is professor of surgery and chief of bariatrics and minimally invasive surgery, Tufts University, Boston. "We wholeheartedly endorse the document," he said.
"We welcome more research--there's always a benefit to more research--but we feel that we have sufficient research to go forward," said Dr. Shikora, who is also the president of ASMBS.
"Our society realized many years ago that this was metabolic surgery, not weight loss surgery. We don't tell patients that they are going to lose a lot of weight and by the way, they also will have improvements in their other diseases. We tell them that they are going to have improvements in their other diseases and by the way, they are going to lose a lot of weight," he said.
Several participants in the world congress disclosed potential conflicts of interest. Dr. Apovian is on the advisory board and is a clinical investigator for several companies including Sanofi-Aventis and Amylin Pharmaceuticals Inc.; Dr. Buse is a clinical investigator or consultant for numerous companies as well as for the National Institutes of Health; Dr. Schauer is on the advisory board of Ethicon Inc. and receives educational grants from Allergan Inc. and Covidien; and Dr. Shikora is a research consultant to Covidien and Ethicon.
BY Nancy Walsh
New York Bureau
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|Publication:||Internal Medicine News|
|Article Type:||Conference news|
|Date:||Oct 15, 2008|
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