Objectives

Primary objective. This study aimed to evaluate the comparative efficacy of EBTs for morbid obesity, addressing the gap left by earlier reviews and providing an updated perspective on the effectiveness of these interventions in light of the evolving evidence base.

Secondary objectives. If heterogeneity among enrolled studies were found, we will assess the reason of heterogeneity for the interpretation of the results of this systematic review.

Review question

We used the patient/population, intervention, comparison, outcome (PICO) as a research question formation and search strategy tool [10].

Population

Patients with morbid obesity (body mass index will be collected for each study).

Intervention

EBTs, including intragastric balloon, DJBL, aspiration therapy, endoscopic gastric plication, primary obesity surgery endoluminal (POSE), and botulinum toxin injection, etc.

Control

Sham and/or lifestyle modification.

Outcome

The primary outcomes will be the common efficacy metric found after systematic review of relevant studies, such as percent excess weight loss (%EWL) or percent total body weight loss (%TBWL).

The final review question is that the comparative the efficacy of EBTs in the treatment of morbid obesity.

Overall study design

This systematic review with network meta-analysis will be performed in accordance with the statement of the Preferred Reporting Items for a Systematic Review and Meta-analysis for systematic review protocols (PRISMA-P) and PRISMA Extension Statement for Reporting of Systematic Reviews Incorporating Network Meta-analyses of Health Care Interventions (PRISMA-NMA) [11–14]. The core protocol of this study was registered at PROSPERO database (CRD42024514249) on Jan 2024. Any amendment in protocol or methodology of this study will be described in the following publication.

Eligibility criteria for the study selection

The publications included in this systematic review must meet the following inclusion and exclusion criteria; Studies will be included if they satisfied the following criteria: (1) randomized controlled studies investigated the compared the efficacy of endoscopic bariatric procedures and controls; (2) studies published in English; and (3) studies in full-text format.

The exclusion criteria is as follows: (1) studies that did not report the treatment outcomes, such as %EWL or %TBWL; (2) case reports and review articles; (3) ineligible research objects, for example, animals or children; and (4) insufficient data regarding treatment outcome.

When there are duplicate data reported from the same institution, the studies with the largest number of enrolled population which may encompass data from all studies will be included.

Information sources (literature search) and study selection process

Firstly, two authors (C.S.B. and E.J.G) will independently perform a web-based core database search (MEDLINE-PubMed, Embase, and the Cochrane Library) using common search formulas (from inception to Feb 2024). Any duplicate articles will be excluded. The titles and abstracts of all identified articles will be reviewed, and irrelevant articles will be excluded. Full-text reviews will subsequently be carried out to determine whether the pre-established inclusion criteria are satisfied in the identified publications. References will be also reviewed to identify any additional relevant studies. Disagreements between the authors will be resolved by discussion or consultation with a third author (G.H.B.). References will be exported into the Endnote software (Clarivate, Berkeley, California, United States).

Searching strategy

The search formulas were made using common keywords relevant to EBTs for the treatment of obesity (inception to Feb 2024). Medical Subjects Headings (MeSH) keywords for MEDLINE and Emtree keywords for Embase were included in the searching formula. The detailed search formulas to identify the relevant articles are described in Table 2.

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Table 2. Searching formula to find the relevant articles.

https://doi.org/10.1371/journal.pone.0308410.t002

Assessment of methodological quality

The methodological quality of the finally included articles will be assessed by two authors (C.S.B., and J.J.L) using the Cochrane Risk of Bias assessment tool version 2.0 (ROB 2.0) [15]. This tool comprises five domains, including bias arising from the randomization process, bias due to deviations from intended interventions, bias due to missing outcome data, bias in measurement of the outcome and bias in selection of the reported result. Each domain comprises a series of signalling questions. Once the signalling questions are answered, the next step is to reach a risk-of-bias judgement, and assign one of three levels to each domain: Low risk of bias, Some concerns or High risk of bias [15].

The overall assessment standard of methodological quality in each study is as follows; Overall low risk of bias is judged to be at low risk of bias for all domains for this result. Overall some concerns is judged to raise some concerns in at least one domain for this result, but not to be at high risk of bias for any domain. Overall high risk of bias is judged to be at high risk of bias in at least one domain for this result or to have some concerns for multiple domains in a way that substantially lowers confidence in the result [15].

Data extraction and additional analyses

Two authors (C.S.B. and E.J.G.) will independently extract the data from each included study and will cross-check the collected data. In cases where data are unclear, the corresponding author of the study will be contacted by e-mail to obtain insight into the original dataset. A descriptive synthesis will be developed by a systematic review process, and network meta-analysis will be performed if the included studies are sufficiently homogenous.

For additional analysis, such as subgroup analysis or meta-regression, the authors will extract the other relevant variables from each included study, such as the age, sex of the participants, geographic origin of the data, year of publication, number of total included patients, type of EBTs, and follow-up duration, etc.

Statistics

Among the statistical approaches of network meta-analysis, frequentist frameworks will be used for this study [16]. Although the Bayesian analysis has been used for the network meta-analysis [17], this poses many limitations, such as the problem of establishing prior probability is rather more complex than the problem of testing the research hypothesis [16]. The following approach is the framework of the frequentist network meta-analysis using random-effects models and we will perform statistical analysis in the following order; 1. generating network geometry to provide an overview of the network relationship. 2 testing for inconsistency (checks the assumption of consistency). 3. creating plots and league table of effect size by treatment in order to illustrate the summary size of comparative effectiveness among various interventions. 4.: determining relative rankings of treatments (cumulative rankings for identifying superiority among interventions). 5. checking for publication bias or effect modifiers for a valid inference from results [16]. STATA software version 15.1 (College Station, Texas, US), including the packages ‘network’ and ‘mvmeta’, will be used for the network meta-analysis.

Ethics

Approval from the institutional review board of the Chuncheon Sacred Heart Hospital was exempted because only anonymized data will be collected from the publications included in the review.

Expected benefits

The previously published meta-analyses were different in terms of the type of EBTs enrolled and the format of the included studies [8, 9]. Both studies were conducted 4–5 years ago and the evidence needs to be updated. This study will provide updated information to clinicians treating obesity and evaluate the quality of the synthesized evidence to help guide treatment decisions. It will also find reasons for heterogeneity among studies that were lacking in previous studies and provide future research perspectives for relevant researchers.

Limitations

If the number of relevant studies conducted in the last 4–5 years is small, it is likely that the synthesized evidence has not been updated much. However, we will follow the protocol of this study to address the limitations of previous studies.