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Completed

NCT Number: NCT07774208

FABP4 Response After Roux-en-Y Gastric Bypass

This retrospective observational cohort study examined serum fatty acid-binding protein 4 (FABP4) dynamics in 28 adults who underwent Roux-en-Y gastric bypass (RYGB), followed at baseline, 3 months, and 6 months. Anthropometric, metabolic, and inflammatory parameters were assessed alongside FABP4, fasting GLP-1, and PYY. Patients were classified as FABP4 responders (decrease from baseline to 6 months) or rebound/non-responders. The study investigated whether FABP4 trajectory after RYGB is associated with the magnitude of weight loss, systemic inflammation, and fasting incretin change.

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Key information

Conditions

Obesity (BMI>30) Bariatric Surgery Bariatric Surgery (Gastric Bypass) Body Weight Body Weight Changes Glucose Metabolism Disorders Hyperinsulinism Inflammation Insulin Resistance Metabolic Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Obesity (BMI > 35) Overnutrition Overweight Pathologic Processes Pathological Conditions, Signs and Symptoms Signs and Symptoms Weight Loss

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Observational

About this study

Sixteen of the 28 participants had previously been enrolled in the control (probiotic-only, non-prebiotic) arm of a completed, registered randomized trial of pre-/probiotic supplementation after RYGB at the same institution (ClinicalTrials.gov Identifier: NCT03517345); these participants received no prebiotic intervention. The remaining 12 participants underwent RYGB by the same surgeon during a comparable period and were not enrolled in that trial. Blood samples from both subgroups had originally been collected and stored at -80°C as part of their respective prospective clinical follow-up. FABP4 concentrations were subsequently measured in these banked, single freeze-thaw samples using a commercial ELISA assay, blinded to patients' weight-loss and inflammatory outcomes, and merged with the anthropometric and biochemical data collected at the corresponding original visits. Because FABP4 assay and the present statistical analysis were performed after clinical follow-up had already been completed for both subgroups, this study is registered retrospectively.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adults who underwent Roux-en-Y gastric bypass (RYGB), performed by a single surgeon
  • Completed baseline, 3-month, and 6-month clinical and anthropometric assessments

Exclusion criteria

  • Use of GLP-1 receptor agonists at any study time point
  • Use of insulin at any study time point
  • Missing 6-month FABP4 measurement (excluded from FABP4-based longitudinal/group analyses; n=1)

Treatment and study plan

Primary outcomes

  1. Measure: Change in serum FABP4 level from baseline to 6 months after RYGB

    Time frame: Time Frame: Baseline, 3 months, 6 months

    Description: FABP4 measured by ELISA; patients classified as responders (decrease) vs. rebound/non-responders (no decrease or increase)

Secondary outcomes

  1. Change in BMI from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in BMI from baseline to 3 and 6 months

  2. Change in body weight from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in body weight from baseline to 3 and 6 months

  3. Change in fat mass (bioelectrical impedance) from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in fat mass and fat-free mass (bioelectrical impedance) from baseline to 3 and 6 months

  4. Change in fat-free mass (bioelectrical impedance) from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in fat mass and fat-free mass (bioelectrical impedance) from baseline to 3 and 6 months

  5. Change in HOMA-IR from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in HOMA-IR from baseline to 3 and 6 months

  6. Change in IL-6 from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in hsCRP and IL-6 from baseline to 3 and 6 months

  7. Change in hsCRP from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in hsCRP and IL-6 from baseline to 3 and 6 months

  8. Change in fasting GLP-1 from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in fasting GLP-1 and PYY from baseline to 3 and 6 months

  9. Change in fasting PYY from baseline to 3 and 6 months

    Time frame: Baseline, 3 months, 6 months

    Change in fasting GLP-1 and PYY from baseline to 3 and 6 months

  10. Baseline-Adjusted 6-Month Change in Body Mass Index (BMI) by FABP4 Response Group

    Time frame: Baseline, 3 months, 6 months

    6-month change in BMI (kg/m²) was compared between FABP4 responder and rebound (non-responder) groups using an ANCOVA model adjusted for baseline (preoperative) serum FABP4 concentration (log-transformed). FABP4 response group was defined by the direction of change in serum FABP4, measured by enzyme-linked immunosorbent assay (ELISA), from baseline to 6 months after Roux-en-Y gastric bypass.

  11. Odds Ratios for Predictors of 6-Month FABP4 Rebound: Early (0-3-Month) BMI Change, Age, and Sex

    Time frame: Baseline, 3 months, 6 months

    Odds ratios (OR) with 95% confidence intervals were estimated using a multivariable logistic regression model to identify predictors of FABP4 rebound status at 6 months after Roux-en-Y gastric bypass. Covariates included early (0-3-month) percentage change in body mass index (BMI), age (years), and sex (male/female). FABP4 rebound was defined as an increase in serum FABP4 concentration, measured by enzyme-linked immunosorbent assay (ELISA), from baseline to 6 months postoperatively.

Sponsors and collaborators

Lead sponsor

Istanbul University

Other

Registry information

Official study title

Heterogeneous Fatty Acid-Binding Protein 4 (FABP4) Responses After Roux-en-Y Gastric Bypass: A Retrospective Observational Cohort Study of Adipokine Remodeling Dissociated From Weight Loss, Inflammation, and Incretin Dynamics

Acronym: FABP4-RYGB

Important dates

Study start
2013
Primary completion
2014
Study completion
2015
First posted
Aug 19, 2026
Registry last updated
Aug 19, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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