DDW: Duodenal Switch Outperforms Gastric Bypass

• Explain to interested patients that this was not a randomized trial and that resolution of comorbidities was assessed according to discontinuation of medications.
  
   
• Note that this study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Three years after surgery, patients with a body mass index of 50 kg/m² or higher who underwent the duodenal switch procedure were less likely to need medications for diabetes, hypertension, and dyslipidemia, than those who underwent Roux-en-Y gastric bypass, Vivek Prachand, M.D., of the University of Chicago, reported at Digestive Disease Week.

The bypass patients were more likely to see a resolution of gastroesophageal reflux disease, Dr. Prachand said.

He and his colleagues had previously shown that duodenal switch resulted in greater weight loss than gastric bypass in the heaviest patients, who are, on average, about 200 pounds over their ideal weight. (See Duodenal Switch Called Bariatric Surgery of Choice for 'Super-Obese')

However, he said, the greater resolution of comorbidities with this procedure occurred independently of the amount of weight lost.

The researchers followed the 350 patients from the weight-loss study for three years to assess the degree of comorbidity resolution in those who underwent duodenal switch (198 patients) and those who had gastric bypass (152 patients).

The prevalence of comorbidities before surgery was similar in both groups, except for a lower rate but greater severity of diabetes in the group undergoing duodenal switch.

Three years after surgery, duodenal switch resulted in greater total weight loss (173.5 versus 118 pounds, P<0.01), a greater percentage of excess weight loss (68.9% versus 54.9%, P<0.01), and lower BMI (33.6 versus 37.2 kg/m², P≤0.05).
 

Those who underwent duodenal switch surgery were more likely to be able to stop using medications for diabetes (100% versus 60%), hypertension (68% versus 39%), and dyslipidemia (72% versus 26.3%), but less likely to discontinue medications for gastroesophageal reflux disease (48.6% versus 76.9%) (P<0.05 for all).

Dr. Prachand said gastric bypass is better at reducing acid reflux because there is little acid production occurring in the remaining small stomach pouch. The procedure also reduces the ability for bile to come back up into the esophagus.

Although duodenal switch surgery resulted in greater weight loss, that did not appear to explain the difference in the resolution of comorbidities, he said.

The mechanisms remain unclear, but research is currently exploring the contribution of gut hormones and other factors.

For example, the hormone GLP1, which affects insulin secretion and glucose sensitivity, might respond differently following the two operations, Dr. Prachand said.

Although duodenal switch surgery appears to have multiple benefits over gastric bypass for the super-obese, surgeons have been reluctant to adopt the procedure, which accounts for fewer than 10% of all weight-loss operations.

One major downside of the procedure is that the resulting malabsorption of calories also applies to vitamins and other nutrients. Because many of the super-obese have vitamin deficiencies even before surgery, there is the potential for malnutrition, Dr. Prachand said.

In addition, he said, duodenal switch surgery is more technically difficult and results in higher morbidity and mortality and alterations in bowel habits.

Dr. Prachand acknowledged that the study was limited by selection bias because the participants were not randomized and by the nonphysiologic measurement of comorbidity resolution.

Dr. Prachand reported no conflicts of interest.