For Super-Obese Patients, Duodenal Switch Beats Gastric Bypass

Duodenal Switch Weight Loss Operation

In the first large, single-institution series directly comparing weight-loss outcomes in super-obese patients, researchers from the University of Chicago found that a newer operation, the duodenal switch, produced substantially better weight-loss outcomes than the standard operation, the Roux-en-Y gastric bypass.

In the October issue of the Annals of Surgery, the researchers report that the duodenal switch (DS) produced greater weight loss than the Roux-en-Y gastric bypass (RYGB) by all measures in patients with a body mass index (BMI) of at least 50. These patients typically carry at least 150 pounds more than their ideal weight.

In this study, patients undergoing duodenal switch were significantly more likely to achieve and maintain successful weight loss--defined as losing more than half of their excess weight--at one year (DS 83.9% vs. RYGB 70.4%) and three years (DS 84.2% vs. RYGB 59.3%) after surgery.

"While there is no single ideal bariatric procedure that can be applied to all severely obese patients, we have generally recommended the duodenal switch for those with a BMI greater than 50," said study author Vivek Prachand, M.D., assistant professor of surgery at the University of Chicago. "This study confirms that approach. Both procedures appear to be reasonably safe in the hands of an experienced team, but the duodenal switch appears to offer a considerable advantage in terms of the amount and possibly the duration of weight loss."

The super obese make up only a fraction of the U.S. obesity pandemic, but their ranks are increasing faster than any other group. When the term was coined in 1987, fewer than one in 2,000 adults in the United States met the criteria of a BMI greater than 50. (A normal BMI is 18.5 to 24.9. From 25 to 29.9 is considered overweight. Thirty or above is considered obese; 40 and above is morbidly obese.) The prevalence of the super-obese has quintupled since then, to one in 400 U.S. adults in 2000, which adds up to more then 50,000 people in the U.S.

At the same time, bariatric or weight-loss surgery has increased from about 16,000 cases in 1992, to 63,000 in 2002, to 171,000 in 2005. The most common surgical procedure for these patients--more than 80 percent of all bariatric operations in 2002--is the gastric bypass, which involves stapling off a large portion of the stomach to make overeating difficult, and rerouting the intestines to reduce the absorption of calories. The duodenal switch--fewer than eight percent of all bariatric procedures performed nationwide--leaves a slightly larger stomach pouch but makes even more drastic alterations to the intestines to limit absorption, particularly of fats and starches.

This study involved 350 consecutive super-obese patients who underwent weight-loss surgery at the University of Chicago Hospitals between Aug. 5, 2002, and Nov. 10, 2005. One hundred ninety-eight patients underwent duodenal switch and 152 had a gastric bypass. More than 80 percent of both groups were female. The average age was 40, but that ranged from 18 to 68. About 92 percent had the surgery performed laparoscopically, through small abdominal incisions.

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