Efficacy and Safety of the Gastric Bypass Stent System on Body Weight and Metabolic Parameters in Obese Patients

This is a prospective, open-label, single-arm study conducted at the department of gastroenterology, Beijing Friendship Hospital, Capital Medical University in China. In this study, all the participants were implanted with the Gastric Bypass Stent System. The device had an intended implantation time of 12 weeks, and the participants were followed up for 24 weeks. Both the implantation and explantation were conducted under general anesthesia. A liquid diet was required for a week after implantation to reduce the risk of early obstruction or migration. All the participants received an oral proton pump inhibitor twice daily during the implantation and within 4 weeks of removal. Primary outcomes were changes in excess weight loss and total weight loss at 12 and 24 weeks. Secondary outcomes included changes in body weight, body mass index (BMI), insulin resistance, liver enzymes, lipids and uric acid at 12 and 24 weeks, and device safety. At the first visit, baseline demographics, medical history, physical examination and laboratory tests were collected. The subjects were scheduled for follow-up visit at 1, 4, 12, 16 and 24 weeks. At each visit, body weight was measured and symptoms were recorded. Blood and fecal samples were collected to observe the changes of metabolic parameters and also to monitor the adverse effects. A complete blood count, liver function, blood glucose, insulin, HbA1C, lipids, uric acid, amylase, iron tests and fecal occult blood were partially or all measured at each visit. Insulin resistance was assessed by the homeostasis model assessment of insulin resistance (HOMA-IR), a value ≧2.69 was considered as insulin resistance. Elevated ALT or AST was considered as abnormal liver enzymes. Primary outcomes were changes in EWL and TWL at 12 and 24 weeks. Secondary outcomes included changes in body weight, BMI, insulin resistance, liver enzymes, lipids, UA at 12 and 24 weeks, and device safety.Analyses were conducted with IBM SPSS Statistics for Windows, version 22.0 (IBM Corporation , Armonk, NY). Data was reported as mean ± standard deviation (SD) . A p value of <0.05 was considered statistically significant. Analyses of body weight changes between different time points were conducted with a paired sample t test. Analyses of metabolic parameters in the blood were calculated by generalized estimating equations (GEE) because of the existence of missing values.

Inclusion criteria

• Age ≥18 and ≤60 years;
• Body mass index ( BMI) ≥30 kg/m2;
• American Society of Anesthesiologists( ASA) Physical Status Classification System:I-II.

Exclusion criteria

• Weight loss of more than 4.5 kg in the past three months, or taking weight-lowering drugs in the past month;
• Taking non-steroidal anti-inflammatory drugs (NSAIDs) or antiplatelet drugs or anticoagulant therapy in the past month;
• Previous diagnosis with type 1 diabetes mellitus;
• Loss of islet β-cell function, C-peptide ≤ 1/2 of the normal low limit, or low C-peptide release curve under glucose load;
• Iron deficiency or iron deficiency anemia;
• Severe organ dysfunction of the heart, the lung, the liver or the kidney;
• Patients who have undergone endoscopic retrograde cholangiopancreatography, or have a history of cholecystitis, gallstones with clinical symptoms or stones larger than 20 mm in diameter; pancreatitis or hepatic abscess;
• History of duodenal ulcer or gastric ulcer;
• Patients with gastrointestinal bleeding or potential bleeding;
• Digestive tract malformation, such as digestive tract atresia or previous gastrointestinal surgery that could cause failure of implantation or affect functioning of the device;
• History of intestinal obstruction in the past year;
• Thyroid dysfunction;
• History of systemic lupus erythematosus or scleroderma;
• Pregnant women or women desiring pregnancy in the next few months.