FORT LEWIS, WA — Is the duodenal-switch (DS) procedure better than the commonly-used gastric bypass (GB) in prompting weight loss and control of coexisting conditions, especially for the super-obese?

An Army study published recently in the Archives of Surgery suggests it might be, but caution clinicians about some significant risks.1

Daniel W. Nelson, DO, from the Department of Surgery, Madigan Army Medical Center, Fort Lewis, WA, and colleagues reviewed the Bariatric Outcomes Longitudinal Database records of 1,545 patients who underwent biliopancreatic diversion with DS and 77,406 patients who underwent Roux-en-Y GB between 2007 and 2010.

The study population, 78% female, had a mean age of 45. Mean follow-up periods were 8.8 months for patients who had the GB procedure and 8.9 months for patients who had the DS procedure, with two-year follow-up data available for 2,688 (3%) of the GB patients and 45 (3%) of the DS patients. The primary surgical approach was laparoscopy for GB patients (92%), though only 50% of DS patients underwent laparoscopy.

The preoperative body mass index (BMI) was significantly greater for the DS group compared with the GB group (52 kg/m2 vs 48 kg/m2; P = .001), and DS patients exhibited a greater prevalence of obesity-associated coexisting disorders. That might have contributed to more complex surgeries, the report suggests.

“DS was associated with significantly greater operative times (191 vs 114 minutes) and estimated blood loss (132 vs 54 mL3), as well as increased need for intraoperative transfusion (1.6% vs. 0.8%) (all P < .001),” the authors wrote. Postoperative infection rates also were significantly higher for DS patients than GB patients (4.5% vs 1.9%; P <.001), and anastomotic leaks were twice as likely to occur in DS patients (1.6% vs 0.8%, P = .001).

In addition, the overall mortality rate for DS patients compared with GB patients, 1.2% and 0.3%, respectively, with a 1.8% mortality rate for super-obese DS patients (those with BMI greater than 50) compared with 0.5% for super-obese GB patients.

On the other hand, DS patients experienced significantly greater BMI reductions than GB patients at all follow-up periods.

“At two or more years’ follow-up, the DS group had attained 43% change in BMI, compared with just 36% in the GB group,” the researchers write, adding, “the DS group saw significantly greater resolution or improvement in most of the well-recognized obesity-related comorbidities, including diabetes, hypertension, hyperlipidemia and obstructive sleep apnea.”

Almost 20% of GB patients had failed to lose 50% of their excess BMI after follow-ups of one and two years, but only 9% of DS patients at one year and 6% at two years were in that situation. For super-obese patients, DS led to a greater percentage of weight loss than GB — 79% vs 67%).

“Although the DS carries a higher relative risk profile than GB, the absolute risk is low,” the researchers conclude. “Among morbidly obese patients, the DS results in superior sustained weight reduction and improved comorbidity control, compared with GB, which may outweigh early perioperative risk.”

1. Nelson DW, Blair KS, Martin MJ. Analysis of Obesity-Related Outcomes and
Bariatric Failure Rates With the Duodenal Switch vs Gastric Bypass for Morbid
Obesity. Arch Surg. 2012 Sep 1;147(9):847-54. PubMed PMID: 22987179