NEW ORLEANS — Gastric bypass surgery resulted in more rapid and greater weight loss over a 2-year period than did gastric band surgery, according to a retrospective analysis of both procedures presented at the annual meeting of NAASO, the Obesity Society.
At 24 months after the procedures, patients who had gastric bypass had a mean excess weight loss of 68%, compared with 37% for those who had gastric band surgery, said Dr. Nancy Puzziferri of the University of Texas Southwestern Medical Center, Dallas. Both types of surgery were nevertheless associated with a significant and sustained excess weight loss benefit, she noted.
Data are scant regarding the relative benefits of both procedures, even though they are the most common operations for obesity in the United States, so Dr. Puzziferri and her colleagues analyzed the outcomes in 1,518 patients aged 18–65 years, of whom 958 underwent gastric bypass and 560 had gastric band surgery between March 1997 and November 2006.
All of the patients met National Institutes of Health eligibility criteria for obesity surgery, which included the following:
▸ A body mass index (BMI) of 35 kg/m
▸ A BMI of 40 or greater.
▸ A history of failed dietary or lifestyle interventions for weight loss.
All of the procedures were done by bariatric surgeons at Southwestern Medical Center.
The patients were seen at 6, 12, 18, and 24 months postoperatively, and once a year thereafter. Their excess weight loss (EWL) was assessed at each visit; successful weight loss was defined as at least 40% EWL at each measurement. Patients with less than 40% EWL were considered to be unsuccessful, Dr. Puzziferri said.
The average preoperative weight for all patients was 311 pounds (range, 167–825 pounds), and the average BMI was 50 (range, 28–115).
At each measurement period, EWL was significantly greater in the bypass patients than it was in the band patients. Bypass patients also lost weight more rapidly than did band patients, Dr. Puzziferri said. (See box.)
Fewer gastric band patients experienced successful weight loss by 2 years. Early success was a predictor of successful weight loss at 24 months for both procedures. However, lack of early success with gastric band did not automatically predict failure at 2 years, Dr. Puzziferri said.
“The weight loss following gastric bypass most likely results from anatomical changes, which confer hormonal and malabsorptive weight loss advantages in addition to restriction, whereas the gradual weight loss with gastric band mimics weight loss resulting from low-fat, low-calorie dietary interventions,” she said.
She added that gastric band patients may need more support to help them make dietary and lifestyle changes so that they can continue to lose weight. “Behavioral practices may be more critical for weight loss success in gastric band patients than in gastric bypass patients, because the band patients lack the changed physiology which promotes weight loss,” she explained.
Dr. Puzziferri cautioned that the study had limitations, including lack of randomization and a relatively short follow-up time. “It is possible that gastric band patients may catch up with the bypass patients with additional time. And bypass patients may regain the weight they have lost. We don't know at this time.”
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