title: Association between Helicobacter pylori infection and multiple sclerosis: A systematic review and meta-analysis.
abstract: OBJECTIVE
  To investigate the association between Helicobacter pylori infection and multiple sclerosis.
  
  
  METHODS
  A comprehensive search of the databases including PubMed/MEDLINE and EMBASE was performed from their dates of inception to January 2016. Inclusion criteria were the observational studies in adult assessing the association between Helicobacter pylori infection and multiple sclerosis. The main outcome was the prevalence of Helicobacter pylori infection comparing between participants with multiple sclerosis and controls. The between-study heterogeneity of effect-size was quantified using the Q statistic and I(2).
  
  
  RESULTS
  The initial search yielded 103 articles. Seventeen articles underwent full-length review and data was extracted from six observational studies involving 1902 participants. There was a statistically significant lower odds Helicobacter pylori infection in multiple sclerosis with pooled odds ratio of 0.59 (95% CI: 0.37-0.94, P=0.03, I(2)=71%). We conducted a univariate meta-regression analysis to assess potential source of heterogeneity. Age of patient and age of onset of multiple sclerosis were significant predictors of association between Helicobacter pylori infection and multiple sclerosis (beta-coefficient =-0.23, SE=0.10, p=0.02 and beta-coefficient =-0.34, SE=0.17, p=0.04, respectively).
  
  
  CONCLUSIONS
  We demonstrate a significant lower prevalence of Helicobacter pylori infection in patients with multiple sclerosis. This pathogen might be a protective factor for developing multiple sclerosis.
authors.affiliation: Department of Internal Medicine, University of Hawaii, Honolulu, HI 96813, USA; Department of Internal Medicine, King Chulalongkorn Memorial Hospital, Bangkok 10330, Thailand. Electronic address: veeravich_j@hotmail.com.
authors.forename: Veeravich
authors.initials: V
authors.lastname: Jaruvongvanich
authors.affiliation: Department of Internal Medicine, Bassett Medical Center and Columbia University College of Physicians and Surgeons, Cooperstown, NY 13326, USA; Department of Preventive and Social Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand. Electronic address: anawin.sanguankeo@bassett.org.
authors.forename: Anawin
authors.initials: A
authors.lastname: Sanguankeo
authors.affiliation: Department of Internal Medicine, King Chulalongkorn Memorial Hospital, Bangkok 10330, Thailand. Electronic address: plan_suthinee@hotmail.com.
authors.forename: Suthinee
authors.initials: S
authors.lastname: Jaruvongvanich
authors.affiliation: Department of Internal Medicine, Bassett Medical Center and Columbia University College of Physicians and Surgeons, Cooperstown, NY 13326, USA; Department of Preventive and Social Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand. Electronic address: sikarin.upala@bassett.org.
authors.forename: Sikarin
authors.initials: S
authors.lastname: Upala
mesh_terms: D004198:Disease Susceptibility; D016481:Helicobacter Infections / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology*; D016480:Helicobacter pylori; D006801:Humans; D009103:Multiple Sclerosis / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology*; D064887:Observational Studies as Topic
keywords: Helicobacter pylori; Meta-analysis; Multiple sclerosis; Observational studies; Systematic review