Gastric bypass surgery may not be the most effective surgery in producing weight loss

Oct 16 2005

The most frequently performed weight-loss surgery, the gastric bypass, may not be the most effective in producing weight loss, according to a preliminary study by physician-scientists at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

The study finds that a more complex procedure, the duodenal switch, was more effective at promoting loss of body weight and body fat than gastric bypass.

The study followed 13 patients who underwent duodenal switch and 33 patients who underwent gastric bypass, all with comparable pre-surgery body mass index (BMI) and body composition. One to two years after surgery, duodenal-switch patients lost 50 percent more weight than gastric-bypass patients (22.3 BMI units lost vs. 15.1 BMI units lost). Furthermore, duodenal-switch patients reduced their body fat to 25.7 percent, compared to 34.0 percent for gastric bypass patients (25 percent body fat is within the normal range for most people). These findings will be presented at the 2005 North American Association for the Study of Obesity (NAASO) meeting in Vancouver on October 16.

"Overall, we found that patients who elect to have duodenal switch end up slimmer than those who choose gastric bypass," says Dr. Gladys W. Strain, director of research for bariatric surgery at NewYork-Presbyterian/Weill Cornell and associate research professor of nutrition in surgery at Weill Medical College of Cornell University. "Previous research has shown that significant weight loss reduces cardiac risk and early mortality."

In the duodenal-switch procedure (also know by its formal name, the biliopancreatic diversion with the duodenal-switch, or BPD/DS), the stomach is reshaped and somewhat reduced in size, creating a sleeve-like or banana shape. Approximately half of the small intestine is bypassed, and the stomach is reconnected to the shortened small intestine. This forms a short channel in which food and digestive juices are mixed. In a gastric bypass, a small gastric pouch is formed from the upper part of the stomach. A section of the upper intestine is then connected to the small gastric pouch through a Y-shaped connection.

Compared with gastric bypass, duodenal switch is less routinely performed, due to its technical difficulty and metabolic concerns, such as the decreased absorption of fat, protein, certain vitamins, and minerals.

In 1999, Dr. Michel Gagner, chief of the division of bariatric surgery at NewYork-Presbyterian/Weill Cornell and professor of surgery at Weill Medical College of Cornell University, performed the world's first laparoscopic duodenal switch. Since then, the procedure has been further modified for high-risk patients so than it can be performed in two stages, resulting in reduced operative mortality.

NewYork-Presbyterian/Weill Cornell offers four laparoscopic surgical weight-loss options, including gastric bypass, duodenal switch, adjustable gastric band, and sleeve gastrectomy. "The availability of these surgeries helps us tailor a treatment plan to each individual patient's needs," says Dr. Gagner.

The study's co-authors include NewYork-Presbyterian/Weill Cornell's Dr. Michel Gagner and Dr. Alfons Pomp, associate attending surgeon, Frank Glenn Faculty Scholar and associate professor of surgery; and NewYork-Presbyterian Hospital/Columbia University Medical Center's Dr. William B. Inabnet, chief of endocrine surgery and associate professor of surgery.

http://www.med.cornell.edu