Long-lasting effects of weight-loss surgeries analyzed

Weight loss in obese Prader-Willi syndrome patients can be sustained, study finds

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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Metabolic and bariatric surgery (MBS) can safely lead to sustained weight loss in Prader-Willi syndrome (PWS) patients, a meta-analysis shows.

“It may indeed be time to take a new look at MBS for patients with PWS,” the researchers wrote.

The study, “Metabolic and bariatric surgery for obesity in Prader Willi syndrome: systematic review and meta-analysis,” was published in the journal Surgery for Obesity and Related Diseases.

PWS is the most common genetic cause of life-threatening obesity. Together with developmental delays and behavioral difficulties, patients with PWS develop an insatiable appetite and food-seeking behaviors.

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Treatment with a lab-made form of growth hormone (GH), which is deficient in PWS, has been shown to improve body composition and cognitive function in these patients. In addition, patients usually undergo dietary restriction and standard weight-loss programs. These strategies remain ineffective in many cases.

MBS has shown efficacy as a treatment for severe obesity. However, its effects in PWS remain poorly characterized.

To shed light on this, a team led by researchers at Drexel University College of Medicine in Philadelphia, Pennsylvania, conducted a meta-analysis of published studies reporting the use of the three most common MBS techniques for PWS patients: laparoscopic sleeve gastrectomy (LSG); gastric bypass (GB); and biliopancreatic diversion (BPD), with or without duodenal switch (DS).

LSG is a minimally-invasive surgery that cuts part of the stomach to reduce its size. The remaining part is closed into a tube shape resembling a sleeve. In GB, a small pouch is created from the stomach and connected directly to the small intestine. This is intended to feel full with less food.

In BPD without DS, a stomach pouch is connected further along the small intestine, whereas in BPD with DS a portion of the stomach is removed, but the part that connects to the duodenum (first part of the small intestine) is maintained and connected to a lower segment of the intestine. The duodenum is connected to the lower part of the small intestine. Overall, in BPD, food bypasses much of the small intestine, which results in fewer calories absorbed and weight loss.

256 publications screened

The researchers analyzed published studies up to July 2022 that reported results on MBS outcomes in PWS. From 256 screened publications, 22 were included in the meta-analysis. Eligibility criteria included haing PWS diagnosis, body mass index (BMI, a measure of body fat) of 35 kg/m2 or greater (indicative of class 2 obesity), and a minimum follow-up of 12 months post-MBS.

In total, from an initial 104 PWS patients who underwent MBS, 67 patients (64%) met the criteria.

Patients (56% males) were placed in three groups, according to the type of intervention; 26 had a LGS (mean age 12.8 years), 28 patients had a BPD (21.4 years), and 10 had GB (18.4 years). BMI before the surgical intervention (baseline) was similar between the three surgery groups.

At one year of follow-up, PWS patients in the LSG group lost a mean of 14.9 kg per square meter (kg/m2) in BMI, those in the GB group a mean of 11.4 kg/m2, and a mean of 15.5 kg/m2 in the BPD group.

The reduction in BMI was still significant three years after surgery in the LSG group, with a mean reduction of 15.2 kg/m2 since baseline.

Those in the GB group also showed a sustained reduction in BMI — mean of 12.1 kg/m2 — at up to two years of follow-up. The BPD-DS group had the most patients followed more than five years. In this case,  the mean reduction in BMI was 10.7 kg/m2 at a seven-year follow-up.

While long-term follow-up data was not available for all patients, statistical analysis showed that the BPD-DS group had the largest weight loss in the long term, with a mean reduction in BMI of 10.9 kg/m2 at 10-years of follow-up.

In contrast, the LSG group presented a slight weight gain after seven years (gain of 0.3 kg/m2, two patients) and after 10 years (0.8 kg/m2 in BMI, also two patients).

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No deaths were reported in any of the surgery groups within one year of follow-up. In the BPD group, there were three revision cases, conducted between the second and fourth year after surgery. One case was related to excessive weight loss and two to severe obesity recurrence.

No surgical complications were reported for LSG and GB procedures. While nutritional complications were seldom reported, there was one case of iron deficiency in the LSG group and one in the BPD group. Two cases of osteoporosis (weak and brittle bones) were reported in the BPD-DS group.

Overall, “the current data on MBS in patients with PWS show that procedures performed today such as the LSG, GB, and BPD with or without DS can safely provide rapid weight loss and alter the natural progression of weight gain seen in these patients,” the study concluded.