One-Year Outcomes After Conversion Bariatric Surgery

NCT07345429 | Active Not Recruiting

• 1 other identifier: MUDU-SBE-SS-01
• Study Type: observational
• Target: 14
• Locations: 1 country
• Sites: 1

Brief Summary

Obesity is a growing global public health problem, and bariatric surgery is currently the most effective treatment for achieving sustained weight loss and improving obesity-related comorbidities. However, a subset of patients experience inadequate weight loss or weight regain following primary bariatric surgery, which may lead to the recurrence of metabolic complications and reduced quality of life. In such cases, conversion bariatric surgery, defined as the surgical conversion from one bariatric procedure to another, is considered an important therapeutic option. Despite the increasing number of conversion procedures, comprehensive longitudinal data evaluating anthropometric, biochemical, and nutritional outcomes after conversion bariatric surgery remain limited. This study aims to prospectively evaluate individuals undergoing conversion bariatric surgery due to weight regain following primary bariatric surgery. Anthropometric measurements, biochemical parameters, and nutritional status will be assessed preoperatively and at 1 year after surgery. By evaluating weight loss outcomes together with metabolic and nutritional changes, this study seeks to provide clinically relevant evidence to guide postoperative follow-up strategies, optimize nutritional management, and support multidisciplinary care in patients undergoing conversion bariatric surgery.

Conditions

Obesity & Overweight; Bariatric Surgery; Revisional Bariatric Surgery

Keywords

conversion bariatric surgery; obesity; nutritional assessment; weight regain; metabolic outcomes; anthropometric measurements

Outcome Measures

Primary Outcomes (10)

• Change in Body Composition Parameters

  Body composition parameters including fat mass, fat percentage, fat-free mass, fat-free mass percentage, skeletal muscle mass, muscle percentage, and extracellular water to total body water ratio assessed using multi-frequency bioelectrical impedance analysis (BIA).

  Preoperative baseline and postoperative 1 year

• Change in Body Weight

  Change in body weight (kg) measured using a digital scale with participants wearing light clothing and no shoes.

  Preoperative baseline and postoperative 1 year

• Change in Body Mass Index (BMI)

  Change in body mass index (kg/m²) calculated from measured body weight and height.

  Preoperative baseline and postoperative 1 year

• Percentage of Total Weight Loss

  Percentage of total weight loss calculated as \[(preoperative weight - postoperative weight) / preoperative weight\] × 100.

  postoperative 1 year

• Percentage of Excess Weight Loss

  Percentage of excess weight loss calculated as \[(preoperative weight - postoperative weight) / (preoperative weight - ideal body weight)\] × 100, with ideal body weight defined as a BMI of 25 kg/m².

  postoperative 1 year

• Change in Waist Circumference

  Waist circumference (cm) measured in the standing position using a non-elastic measuring tape at the midpoint between the lowest rib and the iliac crest.

  Preoperative baseline and postoperative 1 year

• Change in Hip Circumference

  Hip circumference (cm) measured in the standing position at the point of maximum protrusion of the gluteal muscles using a non-elastic measuring tape.

  Preoperative baseline and postoperative 1 year

• Change in Body Fat Percentage (%)

  Body fat percentage measured using multi-frequency bioelectrical impedance analysis (BIA).

  Preoperative baseline and postoperative 1 year

• Change in Fat-Free Mass (kg)

  Fat-free mass measured using multi-frequency bioelectrical impedance analysis (BIA).

  Preoperative baseline and postoperative 1 year

• Change in Skeletal Muscle Mass (kg)

  Skeletal muscle mass measured using multi-frequency bioelectrical impedance analysis (BIA).

  Preoperative baseline and postoperative 1 year

Secondary Outcomes (14)

• Change in Fasting Plasma Glucose

  Preoperative baseline and postoperative 1 year

• Change in Alanine Aminotransferase (ALT)

  Preoperative baseline and postoperative 1 year

• Change in Hematological Parameters

  Preoperative baseline and postoperative 1 year

• Change in Iron Status Parameters

  Preoperative baseline and postoperative 1 year

• Change in Micronutrient and Electrolyte Levels

  Preoperative baseline and postoperative 1 year

Study Arms (1)

Conversion Bariatric Surgery

This cohort includes patients who previously underwent conversion bariatric surgery as part of routine clinical care and were followed observationally. Anthropometric measurements, biochemical parameters, and nutritional status were assessed at the preoperative period and postoperative month 12 (1 year).

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adult patients aged 18-65 years who had previously undergone bariatric surgery and subsequently received conversion bariatric surgery due to suboptimal clinical response, defined as suboptimal weight loss or recurrent weight gain. Participants are followed in routine clinical practice and evaluated preoperatively and at postoperative 1 year for anthropometric, biochemical, nutritional, and physical activity outcomes.

You may qualify if:

• Adults aged 18-45 years
• Previously underwent bariatric surgery
• Subsequently underwent conversion bariatric surgery due to suboptimal clinical response
• Suboptimal clinical response defined as either:
• Suboptimal Clinical Response (SCR): maximum total weight loss (TWL%) of \<20% within 18 months after metabolic and bariatric surgery
• Recurrent Weight Gain (RWG): regaining \>30% of initial postoperative weight loss after achieving initial weight reduction

You may not qualify if:

• Pregnancy or lactation
• Presence of acute illness or infection
• Comorbid conditions that could limit treatment efficacy or compromise safety
• Participation in professional athletic activity

Sponsors & Collaborators

• Medipol University: lead
• Mudanya University: collaborator

Study Sites (1)

Mudanya Univesity

Osmangazi, Bursa, 16160, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Obesity; Overweight

Condition Hierarchy (Ancestors)

Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Officials

• Seher Şen, Assistant Professor

  Mudanya University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor, Principal Investigator

Study Record Dates

• First Submitted: December 17, 2025
• First Posted: January 15, 2026
• Study Start: November 12, 2024
• Primary Completion: January 10, 2026
• Study Completion: February 21, 2026
• Last Updated: February 3, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)