This study compares two surgical techniques used during one-anastomosis gastric bypass (OAGB) surgery for patients with severe obesity. During this operation, surgeons create a bypass of part of the small intestine, and the length of this bypassed segment (called the biliopancreatic limb) affects both weight loss and the risk of nutritional side effects. In this trial, one group of patients has the limb length calculated individually based on the measured total length of their small intestine (TSBL-based method), while the other group receives a limb length based on standard body mass index (BMI) categories (BMI-based method). The study compares weight loss outcomes, improvement of obesity-related health problems, and complication rates between the two approaches over 12 months after surgery. The trial is being conducted at a single center in Almaty, Kazakhstan, and plans to enroll 100 patients total; this record reflects an interim analysis based on the first 75 patients enrolled.
Age between 18 and 65 years
BMI ≥35 kg/m² in non-Asian populations or ≥32.5 kg/m² in Asian populations
Presence or absence of metabolic comorbidities (including type 2 diabetes, hypertension, and dyslipidaemia)
Eligibility for primary one-anastomosis gastric bypass (OAGB)
BMI below the defined thresholds
Severe decompensated cardiac, pulmonary, hepatic, or renal disease
Acute inflammatory conditions
Active gastric or duodenal ulcer
Parallel
TSBL-based biliopancreatic limb length determination
Procedure/SurgeryBiliopancreatic limb length individualized intraoperatively based on measured total small bowel length (TSBL), calculated as BPL = 0.35 × TSBL, prior to laparoscopic one-anastomosis gastric bypass.
BMI-based biliopancreatic limb length determination
Procedure/SurgeryBiliopancreatic limb length determined using standard fixed lengths based on preoperative BMI category (150 cm, 180 cm, or 200 cm), prior to laparoscopic one-anastomosis gastric bypass.
Percentage of Excess Weight Loss (%EWL)
EWL defined as the proportion of weight loss relative to excess baseline weight, with ideal body weight defined as BMI 25 kg/m². Assessed longitudinally over time using linear mixed models.
Percentage of Total Weight Loss (%TWL)
TWL assessed as percentage of total body weight loss relative to baseline weight. Assessed longitudinally over time using linear mixed models.
BMI Change
Change in body mass index (BMI, kg/m²) from baseline over time.
BMI Loss (BMIL)
Reduction in BMI from baseline, expressed as BMI loss (BMIL).
Improvement in Obesity-Related Comorbidities
Change in obesity-related comorbidities, including hypertension and ischemic heart disease, compared between groups.
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National Scientific Center of Surgery named after A.N.Syzganov
Lead sponsor
Kazakh Medical University "Higher School of Public Health"
Collaborator
Klaipėda University
Collaborator
