GRAPEVINE, TEX. — The next frontier in obesity surgery may be its extension to people who are mildly to moderately obese—or even nonobese—so they, too, can reap the metabolic benefits.
Several studies presented at the annual meeting of the American Society for Metabolic and Bariatric Surgery called into question current National Institutes of Health (NIH) guidelines recommending bariatric surgery only for patients with a body mass index greater than 40 kg/m
One such study is an ongoing prospective observational study that, to date, includes 66 patients who had laparoscopic adjustable gastric banding (LAGB). The patients enrolled in the study had either a BMI of 30-35 and comorbidities or a BMI of 35-40 with no comorbidities. The control group consisted of 475 LAGB patients who met the NIH bariatric surgery criteria, said Dr. Jenny J. Choi of Columbia University Medical Center, New York.
At 18 months' follow-up, the NIH nonqualifiers had an average 42% excess weight loss, the same as those in the control group. Although the low-BMI cohort had fewer baseline comorbidities than did controls, those with diabetes, hypertension, gastroesophageal reflux disease, obstructive sleep apnea, hyperlipidemia, stress incontinence, or depression saw improvement in their comorbidities to an extent similar to that of the more obese controls. Indeed, only arthritis was less likely to show significant improvement in the low-BMI group than in controls, she said.
The 6% complication rate in the low-BMI cohort consisted mainly of band slippage or erosion. LAGB is an attractive bariatric procedure for patients with mild to moderate obesity, because even though it results in less weight loss than does gastric bypass, it has substantially less morbidity, Dr. Choi explained.
Dr. Choi noted that hers is not the first study to show that LAGB has significant benefits in patients too thin to qualify for bariatric surgery under the NIH guidelines, which date back to 1991.
For example, a landmark randomized trial by researchers at Monash University, Melbourne, involving 80 patients with a BMI of 30-35 showed an 87% excess weight loss at 2-years' follow-up in the LAGB group, compared with 22% in patients assigned to intensive medical management. The prevalence of the metabolic syndrome—38% at baseline in both study arms—dropped to 3% at 2 years in the LAGB group, versus 24% in the intensive medical management group. Significant quality of life improvements at 2 years were documented in all eight domains of the Short Form-36 for LAGB-treated patients but in only three domains for the nonsurgically managed group (Ann. Intern. Med. 2006;144:625-33).
Researchers at New York University recently reported that LAGB in 53 patients with a mean preoperative BMI of 33.1 dropped their BMI to 25.8 at 2 years' follow-up, with a mean 70% excess weight loss. Of the 53 patients, 49 had at least one baseline obesity-related comorbid condition; substantial improvement was seen in their diabetes, hypertension, asthma, osteoarthritis, hyperlipidemia, obstructive sleep apnea, and depression (Surg. Endosc. 2009;23:1569-73).
A small, randomized Brazilian trial presented at the bariatric surgery meeting showed that two versions of laparoscopic ileal interposition and sleeve gastrectomy had similarly substantial weight-loss and metabolic benefits. Dr. Aureo L. De Paula of Albert Einstein Hospital in São Paulo reported on 38 nonobese type 2 diabetic patients with a mean baseline BMI of 28.5. They were randomized to laparoscopic surgery in which a 170-cm segment of ileum was transposed to the proximal jejunum in conjunction with a sleeve gastrectomy, or to having the same segment of ileum interposed to the proximal duodenum.
The study hypothesis was that the latter procedure, involving both foregut and distal gut mechanisms, would show greater benefit. And although there was a trend in that direction, it did not achieve significance in this small study. Indeed, both procedures proved dramatically effective in reversing diabetes.
For example, in the group as a whole, mean glyosylated hemoglobin (HbA1c) dropped from 8.5% preoperatively to 5.9% at 26 months' follow-up; 35 patients had an HbA1c below 7%, and 35 permanently discontinued all antidiabetic medications. Mean fasting blood glucose went from 207 to 114 mg/dL, postprandial blood glucose fell from 250 to 140 mg/dL, and mean BMI dropped by 5.
Session cochair Dr. Michel Gagner of Mount Sinai Medical Center, Miami Beach, commented that this is “fairly complex” surgery, especially the version involving diversion of the second portion of the duodenum. Why not just study gastric bypass—the most widely performed bariatric operation—in nonobese patients with type 2 diabetes? he asked.
Dr. De Paula replied that he has found gastric bypass to be less effective in reversing type 2 diabetes than the laparoscopic ileal interposition he and his colleagues have developed.