Supplementary Material for: A Meta-Analysis of the Impact of Obesity, Metabolic Syndrome, Insulin Resistance, and Microbiome on the Diagnosis of Barrett’s Esophagus

Background and Aim: The etiology and pathogenesis of Barrett’s esophagus (BE) have been widely studied during recent decades. However, the association between BE and possible risk factors, including abdominal obesity (AO), metabolic syndrome (MetS), insulin resistance (IR), and the microbiome has not reached a consensus and lacks a systematic assessment. The purpose of our study is to evaluate, quantify, and summarize the association between these factors and BE risk. Methods: A systematic search of Pubmed, Embase, and Cochrane Library databases was performed to identify relevant studies before September 2018. Studies were estimated with the OR, the weighted mean difference (WMD), and the 95% CI by using a random effects model. Subgroup analysis and publication bias were also performed. Results: A total of 46 citations were included in the analysis, and 119,273 subjects were analyzed (AO 13, MetS 15, IR 9, and microbiome: 9). The pooled results showed that AO (p < 0.01, OR 1.30, 95% CI 1.11–1.52, I² = 31.9%), MetS (p < 0.01, OR 1.68, 95% CI 1.40–2.01, I² = 87.6%), and IR (p < 0.01, WMD 0.23, 95% CI 0.11–0.35, I² = 55.8%) were all significantly associated with an increased risk of BE, but except for the microbiome (p > 0.05, OR 1.27, 95% CI 0.66–2.43, I² = 46.7%). In addition, subgroup analyses were stratified by waist-to-hip ratio, waist circumference, body mass index, diagnosis criteria, strain type, geographical region, and study design, respectively. Moreover, we observed no evidence of publication bias in Egger’s and Begg’s tests. Conclusions: Our study reveals that AO, MetS, and IR are significantly associated with BE risk, except for the microbiome. The mechanism of BE induced by 3 risk factors should be further explored.