Duodenal Switch Called Bariatric Surgery of Choice for 'Super-Obese'

CHICAGO, Sept. 22 -- For "super-obese" patients, biliopancreatic diversion with duodenal switch appears to achieve better weight loss than Roux-en-Y gastric bypass, found researchers here.

Super-obese patients have a body mass index (BMI) of at least 50 kg/m², reported Vivek N. Prachand, M.D., of the University of Chicago, in the October issue of the Annals of Surgery.

The percentage of excess body weight loss was consistently better for duodenal switch than the more commonly performed Roux-en-Y bypass over three years of follow-up, said Dr. Prachand. In addition, there was better total weight loss and decrease in BMI.

The 198 patients with super obesity who underwent duodenal switch lost significantly more excess body weight at one year (64.1% versus 55.9%), 18 months (71. 9% versus 62.8%), two years (71.6% versus 60.1%), and three years (68.9% versus 54.9%, all P<0.05) than the 152 who opted for Roux-en-Y bypass.

Total weight loss was also statistically greater for duodenal switch (103.1 lb versus 86.3 lb at six months, 171.1 lb versus 128.8 lb at month 18, and 173.5 lb versus 118.0 lb at 36 months, all P<0.01).

Notably, the likelihood of successful weight loss (defined as loss of 50% or more of excess body weight) was significantly improved in patients who underwent duodenal switch compared with Roux-en-Y gastric bypass (83.9% versus 70.4% at 12 months, 90.3% versus 75.9% at 18 months, and 84.2% versus 59.3% at 36 months; all P<0.05).

Mean BMI was initially greater in the duodenal switch group than the gastric bypass group (58.8 kg/m² versus 56.4 kg/m², P=0.0014) but by three years of follow-up had dropped in the duodenal switch group compared with the gastric bypass group (33.6 kg/m² versus 37.2 kg/m², P=0.05).

This "suggests that the difference seen in weight loss is due to greater weight-loss efficacy of [duodenal switch] itself, rather than the greater preoperative weight of the [duodenal switch] group."

While the greater technical complexity and perceived perioperative and nutritional risks of duodenal switch have limited its popularity, there is growing interest in the procedure, the investigators said.

The researchers generally recommended duodenal switch for all super-obese patients, particularly for the 109 participants with a BMI of 60 kg/m² or above. About half of those who opted for gastric bypass did so because their insurer would not cover the other procedure and they did not want to initiate a lengthy appeals process. The other half were split between the belief that duodenal switch was "too radical" and a recommendation by an acquaintance or family member who had a good outcome with the other.

An estimated 3% of men and 7% of women were severely obese (BMI?40 kg/m²) in the National Health and Nutrition Examination Survey (NHANES) in 2003 to 2004. The prevalence of super-obesity accounted for approximately one in 400 U.S. adults in 2000.

"It has been predicted that there would be a convergence of operations towards the gastric bypass, which sits in the middle of the spectrum of difficulty for bariatric procedures," commented Henry Buchwald, M.D., Ph.D., of the University of Minnesota in Minneapolis.

"I think what we are really seeing in this country today, as well as worldwide, is a divergence from the center toward both poles, with more people seeking the lap band, the simplest operation, and the biliopancreatic diversion/duodenal switch, the most difficult operation," he added.

Notably, both procedures were "reasonably safe" with one of 198 duodenal switch patients and none of the gastric bypass patients experiencing 30-day mortality. The one 90-day mortality in the duodenal switch group (0.5%) was presumed to be due to a pulmonary embolism three days after being discharged on postoperative day three.

Though the study did not look at specific complications, the retrospective review of the University of Chicago's prospectively collected bariatric database did not find increased morbidity. Equivalent numbers needed an extended (more than four-day) hospital stay, indicative of a significant postoperative complication. Mean length of stay in the hospital was one day longer for duodenal switch than Roux-en-Y gastric bypass (4.86 versus 3.83 days, P=0.030).

Dr. Prachand acknowledged that both procedures were effective in achieving the 10% to 20% excess body weight loss necessary to improve co-morbidities.

Interestingly, Dr. Buchwald cited his meta-analysis of the world literature comparing gastric bypass to duodenal switch that found comorbidities were more frequently improved with the later procedure. The resolution of diabetes occurred in 84% versus 99%, hyperlipidemia in 97% versus 99%, hypertension 68% versus 83%, and obstructive sleep apnea 80% versus 92%, respectively.

"In the end, each of these procedures is a tool that the patient needs to feel comfortable using, and as such, while we do give a specific recommendation based on the severity of the obesity and the nature of concomitant comorbidities, it is really up to the patient to make the final decision," the authors concluded.