Study Design A single-center cohort study combining prospective and retrospective data collection was conducted. The prospective arm enrolled consecutively admitted patients, while the retrospective arm analyzed previously recorded cases meeting identical eligibility criteria.

Study Setting and Population

The study was performed at the General Surgery Department, Faculty of Medicine, Mansoura University. It included adults aged 18-65 years with morbid obesity eligible for bariatric surgery:

• Body mass index (BMI) ≥ 35 kg/m² with obesity-related comorbidities, or
• BMI 30-34.9 kg/m² with at least one major comorbidity [e.g., type 2 diabetes mellitus (T2DM), hypertension (HTN), obstructive sleep apnea (OSA), dyslipidemia, osteoarthritis (OA), and gastroesophageal reflux disease (GERD)] Study Period
• Prospective: September 2021 - September 2023
• Retrospective: January 2017 - August 2021 Eligibility Criteria Included patients were American Society of Anesthesiology (ASA) class I-III and had failed structured non-surgical weight management for ≥6 months.

Exclusion criteria included endocrine obesity, prior bariatric surgery, severe psychiatric or cognitive disorders, substance abuse, pregnancy, and previous major upper abdominal surgery.

Sample Size

Sample size was calculated based on cost difference between SASI and SAPI procedures using a two-sample means formula. A clinically relevant difference of 500 USD and SD of 700 USD were assumed, yielding:

• Total of 62 patients in the entire cohort
• Adjusted for 10% attrition → 70 total patients Final allocation was approximately 2:1 single anastomosis sleeve ileal bypass (SASI) : single anastomosis plication ileal bypass (SAPI), reflecting real-world recruitment rather than randomization.

Group Allocation Non-randomized assignment was used. Prospective allocation involved shared decision-making within a multidisciplinary team, while retrospective allocation was based on prior surgical records. Influencing factors included cost, availability, insurance, and patient preference.

________________________________________ Methods Preoperative Assessment

Comprehensive evaluation included:

• Detailed medical history and comorbidity assessment
• Nutritional deficiency screening and correction
• Anthropometric measurements
• Laboratory tests
• Imaging (as indicated) Validated Questionnaires
• Physical activity: using The Rapid Assessment of Physical Activity (RAPA)
• Eating behavior: Self-Regulation of Eating Behavior Questionnaire (SREB-Q) and The Eating Attitudes Test (EAT-26)
• Sleep quality: The Pittsburgh Sleep Quality Index (PSQI)
• Socioeconomic status: Fahmy & El-Sherbini scale
• Quality of life (QoL): The Moorehead-Ardelt Quality of Life Questionnaire II (MA-QoL II)

Surgical Procedures

Two laparoscopic techniques were performed:

SASI

• Sleeve gastrectomy over 36-Fr bougie
• 300 cm ileal loop anastomosed to gastric antrum
• Stapled side-to-side stapled gastroileal anastomosis SAPI
• Same, but gastric devascularization and plication over a 36-Fr bougie rather than sleeve gastrectomy Both procedures included leak testing, drain placement, and dual-outlet gastric configuration.

Postoperative Management

Standardized enhanced recovery protocol:

• Early mobilization and VTE prophylaxis
• Proton pump inhibitors and analgesia
• Gradual oral intake from postoperative day 1
• Imaging and lab assessment when indicated
• Early discharge if stable

Cost Analysis

A micro-costing approach was used, including:

• Primary costs: technology, personnel, instruments, disposables, hospitalization, follow-up, supplements
• Secondary costs: readmissions and re-interventions Cost components were calculated using standardized formulas for each item Total cost = Primary + Secondary costs

Cost-effectiveness was evaluated using:

• Cost-effectiveness ratios (CER)
• Incremental cost-effectiveness ratio (ICER)
• Outcomes included percentage of excess weight loss (%EWL), complication rates, readmission, comorbidity remission, and The Bariatric Analysis and Reporting Outcome System (BAROS).

Follow-Up and Outcomes

Follow-up included:

• Weekly (1st month), biweekly (next 2 months), then quarterly (up to 1 year)
• Assessment of weight loss, comorbidities, complications, and QoL

Primary outcome:

• Total cost difference between SASI and SAPI

Secondary outcomes:

• Operative time, length of hospital stay, complications
• %EWL, comorbidity remission
• QoL (MA-QoL II, BAROS)

Statistical Analysis

Performed using SPSS v26:

• Normality: Shapiro-Wilk test
• Continuous data: t-test or Mann-Whitney U
• Categorical data: Chi-square or Fisher's test
• Regression: linear and logistic models
• Significance set at p < 0.05.

Study design This study was designed as a single-center cohort study incorporating both prospective and retrospective components. The prospective arm involved the forward collection of data from consecutively enrolled patients, while the retrospective arm included the analysis of previously recorded data from patients meeting the same eligibility criteria.

Study Setting The study was conducted at the General Surgery Department, Faculty of Medicine, Mansoura University. It included patients presenting with obesity eligible for metabolic and bariatric surgery, defined as body mass index (BMI) ≥ 35 kg/m² regardless of the presence of obesity-related comorbidities. Patients with BMI 30-34.9 kg/m² were included only if associated with at least one obesity-related comorbidity, particularly type 2 diabetes mellitus (T2DM), hypertension (HTN), obstructive sleep apnea (OSA), dyslipidemia, and osteoarthritis (OA), gastroesophageal reflus disease (GERD).

Study Period The study incorporated both prospective and retrospective components. The prospective phase enrolled patients admitted between September 2021 and September 2023, or until attainment of the target sample size. Additionally, a retrospective analysis was performed on prospectively maintained data of patients treated between January 2017 and August 2021, using identical eligibility criteria and data collection parameters.

Eligibility Criteria Patients were considered eligible for inclusion if they were between 18 and 65 years of age and classified as American Society of Anesthesiologists physical status I-III. Eligible participants were those diagnosed with morbid obesity who had previously failed to achieve or maintain a clinically significant weight reduction despite undergoing a structured, supervised non-surgical weight management program for at least six months.

Exclusion Criteria Patients were excluded if obesity was secondary to an identifiable endocrine disorder. Additional exclusion criteria included a history of any previous bariatric surgical intervention, as well as the presence of significant cognitive impairment or major psychiatric illness. Patients demonstrating poor motivation or unwillingness to comply with long-term lifestyle modifications were also excluded. Other exclusion criteria included active substance abuse or alcoholism, pregnancy at the time of enrollment or planned pregnancy within the following 12 months, and a history of previous upper abdominal laparotomy that could potentially alter surgical anatomy or increase operative complexity.

Sample Size The sample size was calculated using the sample size calculator (www.clincalc.com), based on the primary outcome of the study (overall costs). In light of previous literature, Elbanna and coworkers reported that the difference in operative costs between SASI and SAPI ranged from 750 to 900 USD (Elbanna et al., 2020). However, to ensure a conservative estimation and avoid overestimation of effect size, a minimum clinically significant difference of 500 USD was assumed for the present study.

The required sample size was estimated at 31 patients per group, corresponding to a total of 62 patients. To account for potential dropout and loss to follow-up, an additional 10% was added, resulting in an adjusted target of 68.2, rounded to 70 patients. Accordingly, the planned sample size was considered to range between 62 and 70 patients, depending on attrition and completeness of follow-up. Although the observed cohort during the study period ultimately showed an approximate 2:1 distribution between the study groups, this allocation was not predefined in the sample size calculation and resulted from natural recruitment patterns.

Group Allocation Patients were allocated to the study groups based on both prospective recruitment and retrospective inclusion of eligible cases. In the prospective phase, allocation was determined through a shared decision-making process involving the patient and a multidisciplinary bariatric team, including the bariatric surgeon, metabolic physician, dietitian, and psychiatrist. In the retrospective phase, group assignment was based on the procedure that had already been performed and documented in the medical records, applying the same eligibility criteria used in the prospective cohort. Overall, allocation was non-randomized and reflected routine clinical practice within the study setting.

METHODS History Taking A comprehensive preoperative history was obtained from all patients, including the etiology and duration of obesity, associated obesity-related comorbidities, use of obesity-inducing medications, and any positive family history of obesity. Particular attention was paid to the main presenting complaint. The development and progression of obesity-related comorbidities were also documented. Preoperative screening for nutritional deficiencies was routinely performed, with particular focus on deficiencies commonly encountered in patients with morbid obesity. Any identified deficiencies were corrected before surgery.

In addition, validated questionnaires were used to assess preoperative lifestyle and psychosocial parameters:

Physical Activity:

• The Rapid Assessment of Physical Activity (RAPA) The Rapid Assessment of Physical Activity (RAPA) is a brief, validated self-reported questionnaire used to assess physical activity levels in clinical and research settings. It consists of RAPA-1, which evaluates aerobic activity and categorizes participants as sedentary (1-2), underactive (3-5), or active (6-7), and RAPA-2, which assesses strength and flexibility activities, scored categorically from 0 to 3. Results are reported separately, with higher scores indicating greater levels of physical activity.

Eating Behavior:

• Self-Regulation of Eating Behavior Questionnaire (SREB-Q) The Self-Regulation of Eating Behavior Questionnaire is a validated instrument used to assess an individual's ability to control eating behavior in response to internal hunger and satiety cues as well as external influences. It consists of five items rated on a 5-point Likert scale, with two items reverse scored. A total mean score is calculated, with higher scores indicating better self-regulation of eating behavior. Scores are categorized as low (<2.8), moderate (2.8-3.6), or high (>3.6) self-regulation and are reported as both a mean score and categorical level.
• The Eating Attitudes Test (EAT-26) The Eating Attitudes Test-26 (EAT-26) is a widely used screening tool for identifying disordered eating attitudes and behaviors and individuals at risk of eating disorders such as anorexia nervosa and bulimia nervosa. It includes 26 items assessing dieting behaviors, food-related attitudes, and concerns about body weight and shape, and is primarily used as a screening rather than a diagnostic instrument in clinical and research settings. Responses are rated on a 6-point Likert scale and typically recoded from Always (3) to Never (0), with the total score ranging from 0 to 78. An additional behavioral section evaluates risky behaviors such as binge eating and purging but is not included in the total score. A total score of ≥20 indicates a high risk of disordered eating and the need for further clinical assessment, while scores below 20 suggest lower risk. Results are reported as total score and screening category.

Sleep Quality:

• The Pittsburgh Sleep Quality Index (PSQI) The Pittsburgh Sleep Quality Index (PSQI) is a validated self-administered questionnaire used to assess sleep quality and disturbances over the previous month. It comprises 19 items organized into seven components: subjective sleep quality, sleep latency, duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction. Each component is scored from 0 (no difficulty) to 3 (severe difficulty), and a global score is calculated by summing all components, yielding a total range of 0-21 (item 10 is excluded). Higher scores indicate poorer sleep quality, with a commonly used cutoff of >5 defining poor sleep and ≤5 indicating good sleep quality.

Socioeconomic Status:

• Fahmy and El-Sherbini Scale The socioeconomic status (SES) scale is a validated and widely used instrument that assesses socioeconomic level across multiple domains, including education, occupation, income, housing conditions, family size, and access to healthcare. Each domain is assigned a weighted score, and the total SES score is derived by summing all domain scores to reflect the individual's overall socioeconomic position. Based on predefined cutoff values, participants are categorized into low, middle, or high socioeconomic status, with higher scores indicating better socioeconomic conditions. In research, SES is typically reported as either mean ± standard deviation of total scores or as categorical distributions across SES levels.

Quality of Life (QoL):

• The Moorehead-Ardelt Quality of Life Questionnaire II (MA-QoL II) The Moorehead-Ardelt Quality of Life Questionnaire II (MAQ-II) is a validated, obesity-specific instrument used to assess health-related quality of life in patients undergoing weight-loss interventions, including bariatric surgery. It evaluates six psychosocial domains: self-esteem, physical activity, social relationships, work performance, sexual activity, and eating behavior, reflecting perceived rather than clinical outcomes. The questionnaire contains six items scored on a 5-point Likert scale (-0.5 to +0.5), with higher values indicating better quality of life. The total score is calculated by summing all items, yielding a range from -3.0 to +3.0, where higher positive values represent better quality of life. Results are typically reported as mean ± standard deviation and/or categorized into levels ranging from very poor to excellent.

Clinical Examination and Anthropometric Measurements A comprehensive clinical examination was performed to identify any underlying systemic conditions that may influence surgical eligibility or outcomes. The abdomen was examined to detect the presence of previous surgical scars and incisional hernias, which are important considerations in planning bariatric or abdominal procedures. A detailed musculoskeletal and general physical assessment was also conducted to evaluate functional status and obesity-related limitations.

Obesity-Related Anthropometric Parameters

Standardized anthropometric measurements were obtained under uniform conditions:

• Height and weight were measured using calibrated stadiometers and electronic scales, respectively.
• BMI was calculated using the formula: BMI = weight (kg) / height² (m²)
• Waist circumference (WC) and hip circumferences (HC) were measured using a non-stretchable measuring tape to assess central obesity and calculate waist-to-hip ratio.
• Ideal body weight (IBW) was estimated using the formula: IBW = 25 × (height in meters)²
• Excess body weight (EBW) was calculated as: EBW = Actual body weight (kg) - IBW (kg)

10.1. Laboratory and Radiological Investigations All patients underwent a standardized preoperative workup to assess general health status, detect comorbidities, and identify potential contraindications to surgery.

Routine baseline laboratory investigations were performed for all patients and included complete blood count, liver function tests, renal function tests, coagulation profile, fasting blood glucose with 2-hour postprandial glucose, fasting lipid profile, and thyroid function tests. An adrenal hormonal profile was additionally requested when clinically indicated to exclude secondary causes of obesity or related metabolic abnormalities.

Additional Diagnostic Investigations Further evaluations were performed to assess obesity-related complications and surgical risk: Pulmonary function tests and Abdominopelvic ultrasonography.

Special Investigations in Selected Patients Additional targeted investigations were performed based on clinical suspicion or comorbid conditions including Echocardiography, Sleep study (polysomnography), Upper gastrointestinal endoscopy or barium swallow, Serum vitamin D and vitamin B12 levels, and glycosylated hemoglobin.

10.2. Preparation for Surgery Preoperative preparation was standardized for all patients to optimize medical status, reduce perioperative risk, and enhance surgical outcomes.

• Identification and optimization of all correctable medical comorbidities prior to surgery, including cardiovascular, respiratory, endocrine, and metabolic disorders, to ensure fitness for anesthesia and surgical intervention.
• Review and appropriate adjustment of medications that may increase perioperative risk, including anticoagulants, antiplatelets, selected antihypertensives, and hypoglycemic agents, in coordination with relevant specialties.
• Preoperative patient counseling regarding the surgical procedure, expected benefits, and possible intraoperative and postoperative complications.
• Emphasis on the importance of long-term lifestyle modification, including dietary control, physical activity, and adherence to follow-up.
• Obtaining informed written consent for both the surgical procedure and participation in the study after adequate counseling.

Perioperative Prophylaxis

• VTE prophylaxis: Graduated thigh-length compression stockings applied on admission, and LMWH (enoxaparin 40 mg SC) started 12 hours preoperatively. Dose was adjusted for body weight and risk (e.g., 40 mg every 12 hours or ~0.5 mg/kg in high-risk patients ≥120-150 kg), with intensified regimens for patients at increased thromboembolic risk.

• Antimicrobial prophylaxis: Cefazolin administered IV within 30-60 minutes before incision (2 g for <120 kg, 3 g for ≥120 kg) plus metronidazole 500 mg IV for anaerobic coverage. Cefazolin was redosed intraoperatively if surgery exceeded 4 hours or significant blood loss occurred.
• Analgesia and gastric protection: Multimodal preemptive analgesia included paracetamol, NSAIDs (ketorolac when appropriate), gabapentin, and low-dose ketamine in selected cases to reduce opioid requirements. Gastric protection was provided using omeprazole 40 mg daily starting 2 weeks preoperatively, with Helicobacter pylori eradication when indicated.
• Antiemetic prophylaxis: Dexamethasone 4-8 mg IV after induction and use of propofol-based induction of anesthesia were applied to reduce postoperative nausea and vomiting.

Surgical Procedure • SAPI procedure: The SAPI technique was performed laparoscopically under general anesthesia using a standardized multiport approach. After gastric devascularization along the greater curvature using an energy device, gastric plication was performed over a 36-Fr bougie using a two-layer suture technique to create a tubularized stomach. An omega-loop ileal anastomosis was then constructed 300 cm proximal to the ileocecal valve in an isoperistaltic fashion, with a side-to-side stapled anastomosis between the ileum and the gastric antrum approximately 3 cm from the pylorus. The common enterotomy was closed with a two-layer running barbed suture.

• SASI procedure: The SASI technique followed the same devascularization step as SAPI, after which a sleeve gastrectomy was performed over a 36-Fr bougie along the greater curvature from approximately 5 cm proximal to the pylorus to the angle of His. The resected stomach was removed, and an omega-loop ileal anastomosis was created using a 300 cm isoperistaltic ileal limb measured from the ileocecal valve. A side-to-side gastroileal anastomosis was fashioned between the gastric antrum and ileum using a linear stapler, with closure of the enterotomy using a two-layer barbed suture.

• Common steps and completion: In both procedures, a standardized laparoscopic setup was used with systematic abdominal exploration. At the end of surgery, an intraoperative methylene blue leak test was performed to confirm anastomotic integrity. Both techniques resulted in a dual-outlet gastric pathway, and a closed non-suction drain was placed near the anastomosis and typically removed after 24 hours if no complications were detected.

10.3. Postoperative Care and Assessment All patients were initially managed in the standard surgical ward, while admission to the ICU was reserved for high-risk cases or those developing intraoperative or early postoperative complications. Postoperative management followed a standardized enhanced recovery protocol.

General Postoperative Management

• Gastric protection therapy: Omeprazole 40 mg once daily was continued postoperatively for at least 3 months, extended up to 6 months in high-risk patients, to reduce marginal ulceration and promote mucosal healing.
• Analgesia: A multimodal opioid-sparing regimen was used, including paracetamol 1 g IV/PO every 6-8 hours and ketorolac 15-30 mg IV every 6 hours for a limited period. Opioids (nalbuphine 10-20 mg IV every 3-6 hours as needed) were reserved for rescue analgesia in severe pain.
• Antiemetic therapy: Ondansetron 4 mg IV was administered at the end of surgery, with metoclopramide 10 mg IV or droperidol 0.625-1.25 mg IV used as rescue antiemetics when required.

VTE Prevention

• Continued use of graduated compression stockings until full ambulation and early mobilization from the day of surgery.
• enoxaparin 40 mg SC once or twice daily was continued postoperatively with dose adjustment based on weight and risk; higher-risk patients (≥120-150 kg or additional risk factors) received intensified or weight-based dosing with extended prophylaxis for 7-14 days or longer when indicated.

Nutritional Progression

• Clear low-sugar fluids were initiated on the first postoperative day if no leak or intolerance was suspected, with gradual advancement of oral intake according to tolerance and clinical assessment.

Radiological and Laboratory Assessment

• Routine Gastrografin study to exclude leak and assess gastric conduit/anastomosis patency.
• CBC with differential at 24 hours postoperatively to detect infection, bleeding, or inflammatory response.

Diabetes Management

• In T2DM patients, insulin secretagogues were discontinued, and glycemic control was maintained using adjusted insulin regimens based on caloric intake and serial glucose monitoring.

Respiratory Care

• Patients were instructed to perform chest physiotherapy and incentive spirometry to reduce pulmonary complications.

Discharge Criteria and Hospital Stay • Discharge on postoperative day 2 was considered if patients were hemodynamically stable, had controlled pain (score <3), no vomiting for 12 hours, no bleeding, and no evidence of complications such as leakage, infection, or ileus.

Documentation

• Operative time, length of hospital stay, and all intraoperative and early postoperative complications were systematically recorded for all patients.

Outpatient Follow-Up Patients were regularly evaluated in the outpatient clinic for early and late postoperative complications, classified according to the Clavien-Dindo classification system. The follow-up schedule was standardized, with patients evaluated weekly during the first postoperative month, followed by biweekly visits over the subsequent two months. Thereafter, follow-up assessments were conducted quarterly for up to one year.

Postoperative Dietary Regimen and Supplementation Patients were maintained on a liquid diet for the first two weeks following surgery, after which gradual progression of diet was guided according to tolerance and clinical assessment. Routine nutritional supplementation was prescribed to prevent deficiencies in accordance with the American Society for Metabolic and Bariatric Surgery (ASMBS) guidelines.

Follow-Up of Comorbidities Postoperative outcomes were assessed at 6 and 12 months, including body weight, BMI, and percentage of excess weight loss (%EWL).

Anthropometric Assessment Postoperative changes in body composition were assessed at six and twelve months, including: Body weight, BMI, and %EWL.

Anatomical and Radiological Assessment Anatomical and functional evaluation was performed using imaging when clinically indicated. Gastrografin studies assessed anastomotic patency and gastrointestinal transit, while CT volumetry was selectively used to evaluate gastric tube volume and detect complications such as stenosis or twisting.

Functional and Quality of Life Assessment At 12 months postoperatively, validated questionnaires were used to assess outcomes, including physical activity (RAPA), eating behavior (SREB-Q and EAT-26), sleep quality (PSQI), and quality of life and body self-esteem (MAQ-II).

Specific Postoperative Quality of Life

• The Bariatric Analysis and Reporting Outcome System (BAROS) (Oria and Moorehead, 2009) is a standardized, multidimensional tool used to assess outcomes after bariatric surgery. It integrates four domains: percentage of excess weight loss (%EWL), improvement or resolution of obesity-related comorbidities, quality of life (assessed using MAQ-II), and postoperative complications, including reoperations. Each domain is assigned a weighted score, with positive points for weight loss, comorbidity improvement, and quality of life, while deductions are applied for complications.
• The final BAROS score is obtained by summing all positive components and subtracting penalties, yielding a composite value that reflects overall surgical outcome. Results are categorized as Poor (<1), Fair (1-3), Good (3-5), Very Good (5-7), and Excellent (>7), with higher scores indicating better overall postoperative outcomes.

Cost Analysis and Cost Effectiveness Methodology: Actual cost (micro-costing) approach based on Ismail et al. (2015), estimating real resource use per patient, including index admission, readmissions, and re-interventions.

Primary Costs (Index Admission)

• Definition: Total cost of initial hospitalization and surgery, including technology, personnel, reusable instruments, disposables, hospitalization, follow-up visits, and nutritional supplements.
• Technology Costs (TC): Amortized cost of surgical equipment and energy devices (e.g., laparoscopic tower, energy devices, reusable laparoscopic tools), based on purchase price, maintenance, lifespan, usage frequency, and discount rate.
• Personnel Costs (PC): Time-based cost of all staff involved (surgeons, anesthesiologists, nurses, ward staff), calculated using salaries and operative/ward time.
• Reusable Instrument Costs (IC): Per-use cost of reusable surgical instruments, including purchase cost spread over lifespan plus sterilization costs.
• Disposable Costs (DC): Single-use items such as staplers, sutures, trocars, drapes, gloves, IV supplies, antiseptics, and leak test materials.
• Daily Hospitalization Costs: Sum of investigations, medications, consumables, personnel, and hoteling costs per day.
• Follow-up Costs: Number of visits × cost per visit.
• Nutritional Supplements: Monthly cost of supplements × duration of therapy. Secondary Costs (Readmission and Re-intervention Costs)
• Include all post-discharge costs due to complications, readmissions, or additional procedures.
• Calculated using the same components as primary costs (technology, personnel, instruments, disposables, hospital stay, procedures, and follow-up).
• Each event calculated separately and summed per patient. Overall Cost Equation

Total Cost=Primary Costs + Secondary Costs Cost Effectiveness Analysis

• Evaluates total 1-year direct medical cost relative to outcomes such as %EWL, complication rates, comorbidity remission, and BAROS scores.
• Cost-effectiveness ratio (CER) calculated as: cost per unit of effectiveness (C/E).
• Incremental Cost-Effectiveness Ratio (ICER) used to compare procedures, representing additional cost per additional unit of outcome gained.
• ICER calculated separately for each outcome (%EWL, complications, comorbidity remission, BAROS score).

Outcome Measures Primary outcome measures The primary endpoint was the difference between SAPI and SASI in total procedural cost, including both primary costs (index admission and operative expenses) and secondary costs (readmissions, complications, and re-interventions), to comprehensively assess the overall economic burden of each technique.

Secondary outcome measures Secondary outcomes included operative, clinical, and patient-reported measures. These comprised operative time, length of hospital stay, and incidence and severity of postoperative complications. Postoperative changes in body weight, BMI, and %EWL were evaluated to assess weight-loss efficacy, along with analysis of risk factors for weight regain (recidivism). Quality of life (QoL) was assessed using validated questionnaires, and the degree of improvement or remission of obesity-related comorbidities was systematically evaluated.

Definitions of comorbidity outcomes were based on ASMBS guidelines

• T2DM remission: Fasting glucose <100 mg/dL or HbA1c <6% without antidiabetic medications at 1 year; partial improvement defined as ≥25% reduction in fasting glucose and ≥1% reduction in HbA1c with ongoing therapy.
• HTN remission: Blood pressure <120/80 mmHg without antihypertensive medications.
• Dyslipidemia remission: Normal lipid profile without lipid-lowering therapy.
• OSA remission: Apnea-hypopnea index or respiratory disturbance index <5 events/hour without CPAP/BiPAP, confirmed by polysomnography.
• GERD remission: Complete symptom resolution, discontinuation of anti-reflux medications, and normalization of 24-hour pH monitoring.

Statistical Analysis Data were collected, coded, and analyzed using IBM SPSS Statistics (Version 26.0). Variables were classified as categorical, continuous, or ordinal, and normality of continuous data was assessed using the Shapiro-Wilk test. Normally distributed data were presented as mean ± SD, while non-normal or ordinal data were expressed as median with range; categorical variables were reported as frequencies and percentages.

For comparisons between groups, Student's t-test and Mann-Whitney U test were used for continuous variables depending on distribution, and Chi-square or Fisher's exact test was applied for categorical variables. Within-group comparisons were performed using paired t-test or Wilcoxon signed-rank test, while repeated-measures ANOVA or equivalent non-parametric methods were used for longitudinal analysis.

Regression analyses were conducted to identify independent predictors, using linear regression for continuous outcomes and logistic regression for binary outcomes, with multivariate models adjusting for relevant confounders. All tests were two-tailed, with p < 0.05 considered statistically significant.

Ethical Considerations and Study Governance The study was conducted in accordance with established ethical standards for clinical research. Approval was obtained from the Institutional Review Board (code MD.21.03.433) prior to initiation, and all procedures complied with the Declaration of Helsinki. The protocol was registered in a public clinical trials registry (ClinicalTrials.gov; identifier NCT07618598), and reporting followed the STROBE Statement to ensure methodological quality and transparency. Written informed consent was obtained from all participants after full explanation of study aims, procedures, risks, and benefits. Patient confidentiality was strictly maintained through data anonymization and restricted access to authorized research personnel.

The study received no external funding, and no commercial or financial conflicts of interest were declared. The research was conducted with full adherence to principles of scientific integrity and transparency.

Inclusion Criteria:

• Age between 18 and 65 years
• Classified as American Society of Anesthesiologists (ASA) physical status I-III
• Diagnosed with morbid obesity
• Failure to achieve or maintain clinically significant weight loss after ≥6 months of structured, supervised non-surgical weight management
• Participation in a supervised program including dietary modification, behavioral counseling, and lifestyle interventions

Exclusion Criteria:

• Obesity secondary to endocrine disorders (e.g., Cushing's syndrome)
• Previous bariatric or metabolic surgery
• Significant cognitive impairment affecting consent or follow-up
• Major psychiatric illness interfering with adherence or postoperative care
• Active substance abuse or alcoholism
• Pregnancy at enrollment or planned pregnancy within 12 months
• Previous major upper abdominal laparotomy affecting surgical anatomy or increasing operative risk
• Poor motivation or unwillingness to comply with long-term lifestyle modification and follow-up

Deidentified individual participant data (IPD) underlying the results of this study will be made available from the corresponding author upon reasonable request after publication. Requests will be considered for scientifically sound purposes and must include a methodologically sound proposal. Data sharing will be subject to institutional and ethical approval, and a data-sharing agreement to ensure protection of patient confidentiality and compliance with applicable regulations. Supporting documents, including the study protocol and statistical analysis plan, may also be provided upon request.

Individual participant data (IPD) and supporting study documents will be made available upon reasonable request after publication of the primary study results. Data sharing will commence within 6 months following publication and will remain available for a period of up to 5 years thereafter. Access will be granted for scientifically valid proposals and subject to institutional and ethical approval, as well as the execution of a data-sharing agreement to ensure confidentiality and compliance with data protection regulations.

Access to individual participant data (IPD) and supporting study materials will be granted to qualified researchers who submit a scientifically sound proposal and whose request is approved by the corresponding author and relevant institutional/ethical review bodies. Access will be limited to de-identified data only, along with available supporting documents such as the study protocol and statistical analysis plan, where applicable. Data will be shared for non-commercial research purposes only, under a formal data-sharing agreement to ensure confidentiality, data protection, and appropriate use. Requests should be submitted to the corresponding author via email and will be evaluated on a case-by-case basis.