Keywords
Keywords: Metabolic syndrome, Obesity, Weight loss, Gastric bypass.
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Ospanov O, Duysenov G, Yelembayev B and Sultanov K. Study protocol (RCT Clinical trials): Development and implementation of gastric bypass surgery using the "FundoRing" method for the treatment of patients with metabolic syndrome [version 1; peer review: awaiting peer review]. F1000Research 2025, 14:1119 (https://doi.org/10.12688/f1000research.169898.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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Study Protocol
Study protocol (RCT Clinical trials): Development and implementation of gastric bypass surgery using the "FundoRing" method for the treatment of patients with metabolic syndrome
[version 1; peer review: awaiting peer review]
PUBLISHED 15 Oct 2025
OPEN PEER REVIEW
REVIEWER STATUS
This article is included in the All trials matter collection.
Abstract
Corresponding author:
Galymjan Duysenov
Competing interests:
No competing interests were disclosed.
Grant information:
The work was carried out within the framework of grant funding from the Ministry of Education and Science of the Republic of Kazakhstan for 2024-2026, No. AR23490186.
Copyright:
© 2025 Ospanov O et al.
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
How to cite: Ospanov O, Duysenov G, Yelembayev B and Sultanov K. Study protocol (RCT Clinical trials): Development and implementation of gastric bypass surgery using the "FundoRing" method for the treatment of patients with metabolic syndrome [version 1; peer review: awaiting peer review]. F1000Research 2025, 14:1119 (https://doi.org/10.12688/f1000research.169898.1)
First published: 15 Oct 2025, 14:1119 (https://doi.org/10.12688/f1000research.169898.1)
Latest published: 15 Oct 2025, 14:1119 (https://doi.org/10.12688/f1000research.169898.1)
Background
According to the World Health Organization, 2.5 billion adults aged 18 and over are overweight in 2022; more than 890 million of them are obese, and the trend is getting worse; thus by 2035, more than 4 billion people may suffer from obesity.1
In Kazakhstan, the prevalence of obesity among adults is at least 20% of the country’s population. Bariatric and metabolic surgery is an effective treatment for obesity,2 and concomitant conditions such as type 2 diabetes mellitus,3,4 metabolically associated fatty liver disease, reduced steatosis, and liver fibrosis5 are associated with a decrease in mortality and frequency of cardiovascular diseases,6 improved quality of life of patients,7,8 and reduced overall morbidity and mortality from cancer in the future.9
Despite satisfactory postoperative results, they are overshadowed by consequences such as weight regain,10,11 heartburn/GERD,12 dumping syndrome,13 vitamin B1 deficiency,14 B12,15 D,16 E,17 K,18 iron, zinc, calcium, and phosphorus.19
Today, an urgent issue of bariatric surgery remains to improve the effectiveness of primary bariatric operations, preventing the recurrence of obesity by developing new, more effective, time-stable methods of gastric bypass surgery with minimal side effects. Repeated (revision) surgery is associated with technical difficulties due to the presence of adhesions, changes in anatomy, and violations of the normal orientation of tissues, which leads to an increase in the duration of surgery, complications, and mortality compared with the primary performed bariatric surgery.20,21 We have studies on these issues, but the comparison groups and the duration of observation are too small.22
The aim of this study is to develop and improve the immediate and long-term results of gastric bypass surgery for the treatment of metabolic syndrome using the author’s method “FundoRing” in large groups and with longer follow-up.23
The author’s24 idea of the method is physiological reconstruction using the arch (fundus) of the switched-off part of the stomach as an autologous material to create a circular cuff for bandaging the circumference of the upper part of the cut-out small ventricle. Unlike similar methods of banding, the author’s method consists in using a “ring bandage” from the patient’s own living tissues, and not from an allomaterial, which eliminates bedsores and rejection of foreign material, characteristic of standard banding. There is significant groundwork for the project in the form of practical application experience and publication of preliminary results of the “FundoRing” method in specialized BMS journals with the Q1 quartile. However for widespread safe, scientifically based implementation nationwide, it is necessary to evaluate the method on a large sample of patients bycomparing the author’s method with the standard method of performing gastric bypass surgery in BMS.
Methods/design
In a Astana Medical University Clinic, prospective, interventional, open-label, two-arm randomized controlled trial (RCT), one thousand patients will be analyzed and randomly assigned to the main group (n=500), where the author’s method of “FundoRing” will be applied, and to the control group (n=500), where the standard method of one-anastomosis gastric bypass will be applied. A comparison of general surgical, antireflux, bariatric, and metabolic results in both groups will be performed. In the longer, in addition to standard laboratory and instrumental research methods, intraoperative fluorescence imaging in the near-infrared range with the use of indocyanine green using the NIR/ICG method, endoscopic ultrasound scanning of the esophageal-gastric junction, and daily pH-metry of the esophagus and small ventricle will be performed. A study on the quality of life will also be conducted, and a comparative clinical and economic analysis of the developed method will be conducted.
Eligibility criteria
The inclusion criteria:
• BMI 30-50 kg/m2.
• The patient was generally fit for anesthesia (ASA grading 1-2) and surgery.
• The person commits to the need for long-term follow-up.
The exclusion criteria were:
• BMI less than 30 kg/m2 and more than 50 kg/m2.
• Prosthetic (mesh) Hiatal herniorrhaphy or large hiatal hernia;
• Esophageal shortening
• Los Angeles Classification of Oesophagitis (LA grade) C or D reflux esophagitis
• History of surgery on the stomach or esophagus
• Less than 18 or more than 60 years of age
• Not fit for bariatric surgery
• Psychiatric illness
• Patients unwilling or unable to provide informed consent
Randomization: Written informed consent was obtained from each participant before inclusion in the study. Patients who met all the inclusion criteria and none of the exclusion criteria were consecutively included and randomized into one of the three study arms by the study statistician, who was not involved in the enrolment, assignment, or assessment of patients, according to a random allocation sequence generated by Stata 7.0. The randomization list was kept confidential. Allocation concealment was ensured using sequentially numbered, identical, opaque, sealed envelopes (n = 1000). The intervention will be communicated to the patient by a nurse who is not involved in the enrolment or assessment of patients and who will open the sealed envelope during the visit before surgery. Group 1 (A). The patients in Group 1 (n = 500) were treated with laparoscopic one-anastomosis gastric bypass with total wrapping of the fundus of the gastric excluded part and suture cruroplasty if present with hiatal hernia (FundoRingOAGB group); Group 2 (B). The patients in Group 2 (n = 500) were treated with laparoscopic one-anastomosis gastric bypass and with only suture cruroplasty if present with hiatal hernia (OAGB group). In this study, the single-party independent evaluation method is used to evaluate the outcomes of the study. General procedures and monitoring data collection and patient management treatment-related data were collected at stage 1 (before intervention), and follow-up data were collected for 12,24,36,48 and 60 months. Data collection began on the day when the participant signed the informed consent, and continued, until the participant refused to participate for any reason. All source data were stored chronologically for verification. The initial data were transmitted in a timely manner to the paper form of the clinical case report (CRF) and an electronic database located in a secure room at the research site. Access to the research data was limited.
Primary points:
1. Changes in body mass index (Δ-BMI) this measurement will allow us to assess changes in BMI after the intervention. Weight (kg) and height (cm) were combined into BMI (kg/m2). The time frame was the initial, 12, 24.36 months after the operation.
2. Changes in concomitant diseases with an assessment of the corresponding symptoms and are presented as the percentage of patients who have an improvement or disappearance of diabetes, hiatal hernia, and gastroesophageal reflux disease.
3. Changes in quality of life were measured using the Moorhead-Ardelt questionnaire (Quality of Life Questionnaire II) 12 months after surgery.
Secondary points:
1. Performing postoperative intraluminal endoscopy of the esophagus and daily pH monitoring to measure the postoperative DeMister index
2. Perform intraoperative fluorescence imaging in the near-infrared range using indocyanine green according to the NIR/ICG method (IMAGE 1 S Rubina®) on the Karl Storz Endoscopy complex to assess the blood supply to the fundoplication cuff and small ventricle (pouch) in real time.
3. Conducting contrast X-ray examinations and determining insulin levels
Statistical methods: Sample size (n = 1000) Variables with a normal distribution were expressed as the mean and standard deviation (SD), and variables with an abnormal distribution were expressed as the median and interquartile range. Categorical variables were expressed as a numbers and percentages (n, %). In test groups with continuous normally distributed variables, Student’s t-test will be used.
The Mann-Whitney U-test will be used for continuous abnormally distributed data. Categorical variables will be compared using the χ2 or Fisher’s exact criteria; if necessary, categorical variables will be presented as relative risk. Statistical analyse will be conducted based on intention to treat.
Multivariate analysis will be performed using logistic regression and generalized mixed linear regression models, adjusted for any possible distorting covariants and taking into account variability within the center.
A value of p < 0.05 will be considered statistically significant.
The assessment of the primary outcome indicator will be conducted using data from all randomized patients, regardless of whether they followed the treatment protocol or provided complete datasets. In particular, data on the following patients may not be available: those who stopped participating in a clinical trial will be evaluated as if they had completed the study. Those whose scheduled surveys were not carried out on schedule will continue to be considered in the analysis. Missing individual responses to the second questionnaire on quality of life will be replaced by a simple calculation in accordance with the recommendations given in the testing manual. The causes of any missing data will be analyzed, and any random missing data will be processed using multiple calculations and model-based approache, such as mixed models or weighted generalized estimation equations for repeatedly measured results. To verify the reliability of the results, a sensitivity analysis will be performed, considering the assumptions made in the full analysis of the specific case. An adverse event (NIA) refers to any adverse event that occurs during a clinical trial, but does not necessarily have a causal relationship with surgical treatment. Safety assessment was carried out from the moment of receipt of the signature on the informed consent form until the end of the study or until the patient left the study, in accordance with the requirements of the guidelines. Side effects and serious adverse events (SAES) will also be reported. During a clinical trial, NIA leads to hospitalization, prolonged hospitalization, disability, life-threatening illness, death, or a congenital malformation.
All NIA will be registered during the study. These records included the type of NIA (using standard medical terminology), date of occurrence of NIA, date of disappearance/stabilization of NIA, severity of NIA, effect of NIA on surgery, association of NIA with surgery, treatment measures, and their results.
Confidentiality the relevant provisions of the data protection legislation will be respected. Appropriate and necessary precautions will be taken to ensure the confidentiality of medical data and personal information.
Discussion
The main goal of bariatric and metabolic surgery is to effectively reduce body weight and improve quality of life. Currently, there is no single surgery that can solve all long-term problems associated with heartburn, weight regain, and dumping syndrome. More questions arise regarding the presence of concomitant GERD or hiatal hernias. Of course, there are options involving the use of rings, bandages, and primary gastric fundoplication; however Foreign materials always carry the risk of rejection, bedsores, migration, and other consequences.
Currently, one-anastomosis gastric bypass with FundoRing fundoplication is a unique method aimed not only at solving problems in the presence of concomitant GERD or hiatal hernia, but also to prevent postoperative heartburn and dumping syndrome. The presence of a wide fundoplication cuff with double cuff calibration creates a “gastric band” effect from autologous tissues, which slows down the passage of food through the gastric pouch during OAGB. Simultaneously, the wide fundoplication cuff reduces the degree of gastric pocket expansion in OAGB when food enters the stomach. The fundoplication cuff significantly enhanced the restrictive component of the surgical intervention. This reduces the amount of food that at patient can eat. Normalization of body mass index leads to improved health in patients with metabolic syndrome. Despite its short duration, the study may provide important information on improving the effectiveness and improvement of one-anastomosis gastric bypass surgery for effective weight loss, surgical tactics in the presence of hiatal hernia and GERD, prevention of postoperative heartburn, weight regain, and dumping syndrome.
Trial registration: ClinicalTrials.gov ID NCT04834635. Registered on 04 April 2021.
Trial status
Participant recruitment was completed at the time of submission of the initial manuscript. A patient database was created for present study. An analysis of the initial results is currently underway. The work is compliant with the TITAN Guidelines 2025 - governing declaration and use of AI.25
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how to cite this article
Ospanov O, Duysenov G, Yelembayev B and Sultanov K. Study protocol (RCT Clinical trials): Development and implementation of gastric bypass surgery using the "FundoRing" method for the treatment of patients with metabolic syndrome [version 1; peer review: awaiting peer review]. F1000Research 2025, 14:1119 (https://doi.org/10.12688/f1000research.169898.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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