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ASMBS support bariatric surgery for BMI<35 patients
The American Society for Metabolic and Bariatric Surgery (ASMBS) has issued a statement endorsing the use of bariatric surgery, including gastric banding, Roux-en-Y gastric bypass, and sleeve gastrectomy, in patients with a BMI between 30 and 35.
The paper, written by the ASMBS’ Clinical Issues Committee and published in the latest issue of SOARD, says that surgery in the mildly obese population “should be an available option for suitable individuals”.
The authors write that it is apposite to reassess the point at which the benefits of bariatric surgery outweigh the risks, as American private health insurers continue to use a baseline BMI for surgery of 40, or 35 with serious comorbidities, which was set in 1991, despite the subsequent development of new evidence.
“The existing cutoff of BMI was established nearly 20 years ago. There is no current justification on grounds of evidence of clinical effectiveness, cost-effectiveness, ethics, or equity.” ASMBS Clinical Issues Committee
“The existing cutoff of BMI, which excludes those with class I obesity [BMI 30-35], was established nearly 20 years ago,” write the authors. “There is no current justification on grounds of evidence of clinical effectiveness, cost-effectiveness, ethics, or equity that this group should be excluded from life-saving treatment.”
In reaching its conclusions, the paper analysed evidence from five randomised trials and meta-analyses, as well as 16 observational studies. It concluded that bariatric surgery in the mildly obese population had benefits to weight loss, was cost-effective, and led to improved health outcomes, particularly in the case of individuals with type 2 diabetes.
While the paper did not make explicit recommendations about the type of bariatric surgery that should be performed in this group, it notes that gastric banding has a lower rate of early postoperative complications than other options.
However, it is also more dependent on quality follow-up, and is therefore ill-advised if access and funding cannot be assured, it is less effective at treating type 2 diabetes, and many patients are resistant to the idea of having a foreign object implanted into their body. For these reasons, the authors also encourage surgeons to consider gastric bypass and sleeve gastrectomy, particularly for patients with poorly-controlled type 2 diabetes.
“In the final analysis,” the authors write, “it remains up to the judgement of the treating physicians and the patient to choose the option they feel is in the patient’s best interest.”
The paper makes the following observations and recommendations:
- Class I obesity is a well-deﬁned disease that causes or exacerbates multiple other diseases, decreases the duration of life, and decreases the quality of life. The patient with class I obesity should be recognized as deserving treatment for this disease.
- Current options of nonsurgical treatment for class I obesity are not generally effective in achieving a substantial and durable weight reduction.
- For patients with BMI 30–35 who do not achieve substantial and durable weight and co-morbidity improvement with nonsurgical methods, bariatric surgery should be an available option for suitable individuals. The existing cutoff of BMI, which excludes those with class I obesity, was established arbitrarily nearly 20 years ago. There is no current justiﬁcation on grounds of evidence of clinical effectiveness, cost-effectiveness, ethics, or equity that this group should be excluded from life-saving treatment.
- Gastric banding, sleeve gastrectomy, and gastric bypass have been shown in RCTs to be well-tolerated and effective treatment for patients with BMI 30–35 in the short and medium term.
Finding a BMI baseline
The paper notes that the idea that bariatric surgery should be performed on patients with a BMI over 40, or over 35 with major comorbidities, originated from the 1991 National Institutes of Health Consensus Development Conference, as a synthesis of the views of the conference delegates.
However, it notes, bariatric surgery has progressed significantly since 1991: new operative procedures have been developed, almost all operations are now performed laparoscopically, and a great deal of scientific evidence has been produced on the benefits and and hazards of surgery in different populations.
“Give the major changes that have occurred in this field,” write the authors, “it is appropriate to review the data now available, and in the context of bariatric surgery as it is currently practiced, consider modification of the arbitrary recommendations established 20 years ago.”
The authors note that surgery should only considered after nonsurgical therapy has been attempted and has proved unsuccessful. However, the evidence suggests the majority of patients with a BMI of 30-35 will not benefit significantly from non-surgical treatment programmes, including diet, exercise, drugs, and behavioural therapy: the randomised controlled trials included in the literature they analysed pointed towards most people losing an average of two to six kilograms at one year, with difficulty maintaining this loss afterwards.
The authors acknowledge that there were significant groups of patients in the lifestyle intervention trials that did manage to achieve weight loss and glycemic control, which suggests that it is a valid option for some. “Unfortunately,” they write, “intense lifestyle and behavioural interventions are often not practical or sustainable in everyday practice outside of a clinical trial.”