MICROBIOLOGYExtragastric infection of Helicobacter pylori and alopecia areata: a systematic review and meta-analysisGhazvini, Kiarasha,b; Yamaoka, Yoshioc,d; Karbalaei, Mohsene; Keikha, Masouda,b,f Author Information aAntimicrobial Resistance Research Center bDepartment of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran cOita University Faculty of Medicine, Yufu, Oita, Japan dDepartment of Medicine, Baylor College of Medicine, Houston, Texas, USA eDepartment of Microbiology and Virology, School of Medicine, Jiroft University of Medical Sciences, Jiroft fStudent Research Committee, Mashhad University of Medical Sciences, Mashhad, Iran. Correspondence to Masoud Keikha, Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Tel: +98 513 801 2589; e-mail: [email protected] Received 25 November, 2020 Revised 20 January, 2021 Accepted 21 January, 2021 Reviews and Research in Medical Microbiology: January 2022 - Volume 33 - Issue 1 - p e114-e118 doi: 10.1097/MRM.0000000000000276 Buy Metrics Abstract Alopecia areata is an autoimmune cutaneous disease, and the involved mechanism in its pathogenesis has not yet been properly identified. Based on the available evidences, the prevalence of alopecia areata is more common than other autoimmune disorders that caused by Helicobacter pylori infection such as autoimmune thyroiditis, psoriasis, celiac, and Sjogren's syndrome. In addition, previous published reports have shown that antibiotic therapy can cure alopecia areata. Hence, it seems that there is a probable relationship between infection with H. pylori and alopecia areata. In general, the main purpose of this study was to statistically evaluate the infection with this bacterium and its progression to alopecia areata. Because, the available documents had controversial results, we evaluated the data from 926 cases to investigate the relationship between infection with H. pylori and alopecia areata. According to our statistical analysis, we found that the incidence of H. pylori infection among alopecia areata cases is high, also our findings revealed that there is significant association between H. pylori infection and susceptibility to alopecia areata (odds ratio: 1.57; 1.19–2.05 with 95% confidence intervals). Based on the current results, H. pylori infection can be considered as a risk factor for alopecia areata development. Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.