Global prevalence of Helicobacter pylori infection among individuals with obesity: A protocol for a systematic review and meta‐analysis

Abstract Background and Aims Modern populations are prone to obesity, as sedentary lifestyles prevail globally. Previous research has shown that obesity and Helicobacter pylori are mutually associated. However, the global prevalence of H. pylori among individuals with obesity is not yet determined. Methods A comprehensive search will be conducted in PubMed, Scopus, and Web of Science online databases for studies that have reported the prevalence of H. pylori infection among individuals with obesity. Cross‐sectional, case–control, and cohort studies will be included if reported sufficient data. Records screening, data extraction, and quality assessment will be done by independent reviewers. Joanna Bridge Institute checklist for prevalence studies will be used to appraise the included studies. Prevalence will be pooled using random effect models. Heterogeneity will be quantified by I 2 and p value. Subgroup analyses and meta‐regression will be utilized to address the sources of residual between‐study heterogeneity. Discussion Understanding the regional and global occurrence of H. pylori infection in individuals with obesity can provide valuable insights for health policymakers and clinicians to devise proficient diagnostic and eradication strategies, thereby enhancing postoperative outcomes for patients undergoing bariatric surgery. The study's strength will lie in not being restricted to language and time of publication, comprehensive investigation of regional and pre‐ and posteradication estimates, and the effects of time trends and sociodemographic indices on H. pylori prevalence. However, potential heterogeneity in methodologies used across prevalence studies could affect the interpretation of the results. Additionally, the study relies on previously published studies, limiting data quality and completeness.


| REVIEW QUESTION
The review will be interested in individuals with obesity as the population and those who have concurrent obesity and H. pylori as the outcome condition. A comprehensive collection of studies from various regions worldwide will be compiled, specifically seeking favorable data that can be combined to estimate the global prevalence of H. pylori among individuals with obesity.
Additionally, this study seeks to explore the potential influence of population-level factors on the relationship between obesity and H. pylori. Specifically, aims to determine the prevalence of H. pylori in the countries under investigation, categorized according to WHO regional groupings and Sociodemographic Index (SDI) classifications, while also examining how this prevalence varies across different age groups.

| MATERIAL AND METHODS
This protocol for systematic review and meta-analysis is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis protocols (PRISMA-P) 2015 Guidelines. 13 A completed PRISMA-P checklist is provided in the Supporting Information: Material 1.

| Data sources and search strategy
The search will be conducted in the PubMed, Scopus, and Web of Science online databases. The search strategy is a combination of "H. pylori," "obesity," and related keywords and is provided in the Supporting Information: Material 2. The systematic review and meta-analysis will adhere to the PRISMA guideline, ensuring a rigorous approach to the development, conduct, and reporting of the study. 14

| Screening for eligibility
Two reviewers will independently conduct the primary screening based on the titles and abstracts using Rayyan online tool for managing systematic reviews. 15 The records that pass the primary screening process will be then assessed for eligibility based on the full articles. Disagreements will be resolved through discussions. In case of unavailable full texts, the reviewers will contact the authors through their email addresses and will await for at least 1 month for responses. In case of missing data, if crucial, the reviewers will contact the authors for clarifications, and if no responses were received, the studies will be excluded from the review.
Published and preprint observational studies (including cohort, cross-sectional, and case-control studies), posters, and conference Highlights • Obesity and H. pylori infection are mutually associated, but the global prevalence of H. pylori among individuals with obesity is unknown.
• This study aims to conduct a comprehensive search and meta-analysis of studies reporting the prevalence of H.
pylori infection among individuals with obesity, regardless of language and time of publication, to provide a more accurate estimate of the global prevalence.
• The results of this study can guide health policymakers and clinicians in developing effective diagnostic and eradication practices for H. pylori infection in individuals with obesity, as well as improving postoperative outcomes for bariatric surgery patients. abstracts will be eligible for inclusion if reported the prevalence of H. pylori among individuals with obesity. No time and language restrictions will be applied to avoid bias.

| Data extraction
Data will be extracted into Excel spreadsheets in duplicate. Two reviewers will independently recheck the extracted data to detect any errors. Study-level characteristics, including first author, publication year, publication type, study year(s), study country, sample size (individuals with obesity), number of individuals with H. pylori infection, mean population age, male-to-female ratio, criteria for obesity, and detection tests will be extracted from the included studies.

| Quality assessment
Joanna Bridge Institute checklist for prevalence studies will be utilized to assess the quality of the included studies by two independent reviewers. Disagreements will be resolved by discussion. The checklist is available in the Supporting Information: Material 3.

| Analyses
Stata version 16 (StataCorp) will be utilized for analyses. Using a random-effects model (DerSimonian-Laird method), the pooled effect sizes will be reported as percentage and 95% confidence and prediction intervals. Each outcome will be transformed using Freeman-Tukey double arc-sine method to minimize the bias induced by the effect of extremely high or low data on the pooled estimate. 16 Cochrane's Q statistic, I 2 , and p-value will be used to quantify the residual between-study heterogeneity. I 2 of 25%, 50%, and 75% will be interpreted as low, moderate, and high heterogeneity, respectively. 17 Forest plots will be employed to facilitate visual representations.
Subgroup and meta-regression analyses will be used to detect the possible sources of residual between-study heterogeneity and to report the pooled estimates for different conditions of major predictive moderators. Major grouping moderators will be gender ratio, mean age, countries, WHO regional classification, SDI classifications, time the study was conducted, sample size, history of eradication, and diagnostic test. In addition, a subgroup analysis will be done to detect the possible discrepancies between the results of peer-reviewed versus nonpeerreviewed reports. A table will be developed to present the results of subgroup and meta-regression analyses. Publication bias will be avoided in this systematic review and meta-analysis, as it has been discouraged for meta-analyses of proportion studies. 18

| Ethical considerations
Given the absence of human study participants, ethical clearance will not be necessary for conducting this systematic review and metaanalysis. The findings derived from this review are intended to be communicated through globally recognized scientific journals that adhere to rigorous peer-reviewed standards.

| DISCUSSION
Previous systematic reviews and meta-analyses have estimated the worldwide prevalence of obesity and H. pylori infection, separately. 1,6 Nonetheless, the global prevalence of H. pylori infection among individuals with obesity remains unknown. Considering a narrative review by Carabotti et al., 19 this will be the first systematic review and meta-analysis on the worldwide prevalence of H. pylori infection among individuals with obesity.
An evidence-supported estimation of the regional and global prevalence of H. pylori will be greatly helpful to health policymakers and clinicians as it has been demonstrated that H. pylori eradication strategies should be made considering its prevalence among the target population. 20 Therefore, diagnostic and therapeutic strategies could differ from place to place depending on the prevalence of H. pylori. These strategies could include whether any diagnostic tests should be done, the test of choice, and the populations that should be tested. 21 Consequently, practicing without insufficient evidence can greatly impact the public health economy.
Bariatric surgery is widely recognized as an effective therapeutic intervention for individuals with obesity, particularly those with severe forms of the condition. Before performing this procedure, bariatric surgeons commonly opt to eliminate H. pylori, although its necessity remains a subject of debate. 19 Research has demonstrated that eradicating H. pylori before bariatric surgery is associated with improved postoperative outcomes. 19 Nevertheless, there is ongoing controversy regarding the need for confirmatory post-eradication testing, resulting in some patients undergoing surgery without complete eradication of H. pylori. 22,23 Consequently, understanding the prevalence of H. pylori after eradication, both globally and regionally, could provide valuable insights to surgeons in formulating appropriate strategies.

| Strengths and limitations
This study will be the first systematic review and meta-analysis that measures the global and regional prevalence of H. pylori infection among individuals with obesity. The included studies will not be limited by the publishing language, therefore minimalizing the language bias and providing better estimations for regional H. pylori prevalence. A meticulous investigation of the data will provide evidence of the effects of regional evaluations, pre-and SADEGHI and DEHDARI EBRAHIMI 23. Valadares EC, Gestic MA, Utrini MP, Chaim FDM, Chaim EA, Cazzo E Pre-operative screening of Helicobacter pylori in bariatric patients: is histopathological analysis necessary Arq Gastroenterol. 2022;59(2): 275-280.

SUPPORTING INFORMATION
Additional supporting information can be found online in the Supporting Information section at the end of this article.
How to cite this article: Sadeghi A, Dehdari Ebrahimi N.