The duodenal switch procedure is more effective than the stomach bypass in achieving weight loss in patients who are “super obese,” defined as having a BMI of at least 50, new research suggests.

BMI, or “body mass index,” is the ratio of weight to height, which is commonly used to determine if a person is at a healthy weight.

The duodenal switch procedure involves the partial removal of the stomach, which results in a lower capacity for food. A small portion of the duodenum, the top of the small intestine, is also removed to decrease food absorption.

The stomach bypass is an effective weight-loss operation for patients with a BMI between 35 and 50. For super-obese patients, however, this operation is associated with failure rates approaching 40 percent, according to the report in the Annals of Surgery.

“There has been a perception amongst…surgeons that the duodenal switch might provide better weight loss than (stomach) bypass in super-obese individuals,” lead author Dr. Vivek N. Prachand, from the University of Chicago, said in a statement.

However, surgeons have been hesitant to adopt the switch operation since it is more technically demanding than stomach bypass, carries a greater risk of nutritional deficiencies, and requires life-long patient follow-up, Prachand explained. To make a convincing argument for this operation, a study would need to prove that it provides significant advantages over stomach bypass, he added.

The current study, “the first large single institution series directly comparing weight-loss outcomes in super-obese patients” treated with these operations, may provide such proof.

Prachand and colleagues report that re-operation rates within 60 days were similar among the 198 patients who underwent duodenal switch (9.6 percent) and the 152 patients treated with stomach bypass (11.2 percent). There was one death within 90 days in the duodenal switch group and none among the stomach bypass patients.

The excess body weight loss in the duodenal switch group was consistently about 10 percentage points higher than in the stomach bypass group at 12, 24, and 36 months, postoperatively. For example, the excess body weight loss at 36 months was 71.6 percent and 60.1 percent in the duodenal switch and stomach bypass groups, respectively.

In keeping with these findings, the likelihood of successful weight loss, defined as an excess body weight loss of greater than 50 percent, was also significantly higher in the duodenal switch group. At 36 months, the weight loss persisted, at 84.2 percent and 59.3 percent in the duodenal switch and stomach bypass groups, respectively.

“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,” Prachand concluded.

SOURCE: Annals of Surgery October 2006.