PWS study examines lasting effects of metabolic, bariatric surgery
Metabolic and bariatric surgery (MBS) can safely induce sustained weight loss in patients with Prader-Willi syndrome (PWS), a meta-analysis shows.
“It may indeed be time to revisit MBS in PWS patients,” the researchers wrote.
Research, “Metabolic and bariatric surgery for obesity in Prader Willi syndrome: a systematic review and meta-analysis,” published in the journal Surgery for obesity and related diseases.
PWS is the most common genetic cause of life-threatening obesity. Along with developmental delays and behavioral difficulties, individuals with PWS develop insatiable appetites and food-seeking behaviors.
Treatment with laboratory-made growth hormone (GH) in PWS-deficient PWS has been shown to improve body composition and cognitive function in these patients. In addition, patients typically undergo dietary restrictions and standard weight loss programs. In many cases, these strategies remain ineffective.
MBS has shown efficacy in treating severe obesity. However, its effect on PWS is still not fully characterized.
To shed light on this, a team led by researchers at Drexel University School of Medicine in Philadelphia, Pennsylvania, conducted a meta-analysis of published studies reporting the use of the three most common MBS techniques in patients with PWS: laparoscopic Sleeve gastrectomy (LSG); gastric bypass (GB); and biliopancreatic diversion (BPD), with or without duodenal diversion (DS).
LSG is a minimally invasive procedure in which part of the stomach is cut to reduce its size. The remainder is closed into a sleeve-like tube. In GB, a pouch arises from the stomach and connects directly to the small intestine. This is about feeling full with less food.
In BPD without DS, the stomach pouch connects further along the small intestine, while in BPD with DS, part of the stomach is removed, but the part connected to the duodenum (the first part of the small intestine) is preserved and connected to the bowel the next paragraph. The duodenum is connected to the lower part of the small intestine. Overall, in BPD, food bypasses most of the small intestine, resulting in fewer calories absorbed and weight loss.
256 publications screened
Researchers analyzed published studies up to July 2022 that reported results for MBS outcomes in PWS. From 256 screened publications, 22 were included in the meta-analysis. Eligibility criteria included a PWS diagnosis, a body mass index (BMI, a measure of body fat) of 35 kg/m2 or higher (indicating grade 2 obesity), and at least 12 months of follow-up after MBS.
A total of 104 PWS patients underwent MBS, of whom 67 (64%) met the criteria.
Patients (56% male) were divided into three groups according to the type of intervention; 26 patients had LGS (mean age 12.8 years), 28 patients had BPD (21.4 years), and 10 patients had GB (18.4 years) . BMI before surgical intervention (baseline) was similar among the three surgical groups.
At one-year follow-up, BMI decreased by an average of 14.9 kilograms per square meter (kg/m2) in PWS patients in the LSG group, 11.4 kg/m2 in the GB group, and 15.5 kg/m2 in the BPD group.
The reduction in BMI remained significant three years after surgery in the LSG group, with a mean reduction of 15.2 kg/m2 from baseline.
Participants in the GB group also experienced a consistent decrease in BMI — an average of 12.1 kg/m2 — during up to two years of follow-up. The BPD-DS group had the most patients and was followed for more than five years. In this case, the mean reduction in BMI was 10.7 kg/m2 over seven years of follow-up.
Although long-term follow-up data were not available for all patients, statistical analysis showed that the BPD-DS group had the greatest long-term weight loss, with an average decrease in BMI of 10.9 kg/m2 at 10 years of follow-up.
In contrast, the LSG group had a slight increase in body weight after 7 years (increase of 0.3 kg/m2, also in two patients) and after 10 years (increase of BMI of 0.8 kg/m2, also in two patients).
During one year of follow-up, no deaths were reported in any surgery group. In the BPD group, there were 3 revision cases, performed between the second and fourth postoperative year. One case was associated with excessive weight loss and 2 cases were associated with recurrent severe obesity.
No surgical complications were reported for LSG and GB procedures. Although nutritional complications were rarely reported, there was 1 case of iron deficiency in both the LSG and BPD groups. Two cases of osteoporosis (weak and brittle bones) were reported in the BPD-DS group.
Overall, “current data on MBS in PWS patients suggest that procedures performed today, such as LSG, GB, and BPD, with or without DS, can safely provide rapid weight loss and alter the natural course of weight gain in these patients,” the study concluded draw conclusions.