RYGB showed better nutritional outcomes than duodenal switch



WASHINGTON – Despite better excess weight loss outcomes from the biliopancreatic diversion with duodenal switch, the Roux-en-Y gastric bypass procedure was associated with better nutritional outcomes in the superobese, according to the results of a prospective cohort study presented at this year’s American College of Surgeons Clinical Congress.

Investigators retrospectively analyzed data collected prospectively from 350 consecutive superobese patients, who underwent either biliopancreatic diversion with duodenal switch (BPD/DS; n = 198) or Roux-en-Y gastric bypass surgery (RYGB; n = 152), and compared long-term nutritional outcomes in each cohort. The research was conducted by Dr. Marc Ward and his colleagues at the University of Chicago, who presented the results.

The cohorts were self-selected and equally distributed across the sexes; each group’s mean age was just under 41 years. The mean body mass index (BMI) in the BPD/DS group was 59 kg/m2 and was 56 kg/m2 in RYGB. The preoperative body weight in the BPD/DS group was higher than that in the RYGB group (range, 267 lbs to 597 lbs. vs. 240 lbs to 505 lbs, respectively).

Although the BPD/DS had higher morbidity and mortality rates than did the RYGB, as well as more complications, such as altered bowel habits, the BPD/DS is associated with better comorbidity resolution independent of weight loss, and up to 20% greater excess weight loss in superobese patients. Superobesity is defined as having a BMI of 50 kg/m2 and above.

Because the reduction in intestinal absorptive surface area in BPD/DS is greater than in RYGB, the researchers theorized that the resultant nutritional deficiencies might be clinically significant enough to consider when counseling patients on procedure selection.

At seven postoperative follow-up points between 6 months and 8 years, the investigators obtained a variety of nutritional parameters from each group. Patients were given nutritional supplementation as clinically indicated.

Dr. Ward said that while he and his colleagues expected the BPD/DS group to have lower nutritional values, "We didn’t expect that 75% of our patients would have, at 4 years out, a below-normal level of vitamin A, compared to 23% in the RYGB patients."

There were similar surprises for other nutritional markers: At all time points, the BPD/DS group also had significantly more nutritional deficiencies than did the RYGB group in fat-soluble vitamins D and E, and in minerals selenium and zinc. Between years 1 and 3, iron values were near parity at about 20%, although the BPD/DS group was still more deficient, and at year 8 had more than double the rate of iron deficiency as RYGB patients.

Values for albumin, vitamin B12, ferritin, folate, and parathyroid hormone, however, were not significantly different between the two groups. Dr. Ward said that low nutritional values in patients, "does not necessarily mean they are developing symptoms or can’t be treated with supplementation."

Only one RYGB patient underwent revision because of insufficient weight loss, whereas five BPD/DS patients underwent revision, all for malnutrition.

"It’s absolutely crucial for people who elect to have a duodenal switch operation to have long-term, life-long nutritional follow-up," Dr. Ward told the audience. He also said that clinicians should closely evaluate their patients’ level of commitment to compliance over the long-term when discussing bariatric procedures.

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