title: The protective effect of alcohol on developing rheumatoid arthritis: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Our aim was to establish whether alcohol protects against RA development and to determine whether this effect is influenced by alcohol dose, duration and serological status through systematically reviewing the literature and undertaking a meta-analysis.
  
  
  METHODS
  We searched Medline/EMBASE (1946 to July 2012) using the terms rheumatoid arthritis.mp or arthritis, rheumatoid/ and alcohol.mp or ethanol/. Manuscript bibliographies were reviewed. Observational studies were included that were case-control/cohort, examined the relationship between alcohol and RA risk and reported or allowed the calculation of effect size data [odds ratios (ORs)/relative risks (RRs) with 95% CIs] in drinkers vs non-drinkers. A random-effects model was used to estimate pooled ORs/RRs. Dose-risk relationships were evaluated by trend tests. RESULTS. Nine studies (from 893 articles) met our inclusion criteria, comprising six case-control (3564 cases; 8477 controls) and three cohort studies (444 RA cases; 84 421 individuals). A significant protective effect of alcohol on RA risk was observed-summary OR for RA in drinkers vs non-drinkers 0.78 (95% CI 0.63, 0.96). This effect was confined to ACPA-positive RA-summary OR 0.52 (95% CI 0.36, 0.76), with no significant risk reduction seen for ACPA-negative RA-summary OR 0.74 (95% CI 0.53, 1.05). Subgroup analysis by study design identified a significant relationship in case-control but not cohort studies.
  
  
  CONCLUSIONS
  Alcohol intake is inversely associated with ACPA-positive RA, suggesting a protective effect. As this finding is confined to case-control studies further research is required with prospective cohort studies incorporating ACPA status to confirm this relationship.
authors.affiliation: Department of Medical and Molecular Genetics, King's College London, 8th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London SE1 9RT, UK. ian.scott@kcl.ac.uk
authors.forename: Ian C
authors.initials: IC
authors.lastname: Scott
authors.forename: Rachael
authors.initials: R
authors.lastname: Tan
authors.forename: Daniel
authors.initials: D
authors.lastname: Stahl
authors.forename: Sophia
authors.initials: S
authors.lastname: Steer
authors.forename: Cathryn M
authors.initials: CM
authors.lastname: Lewis
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Cope
mesh_terms: D000328:Adult; D000368:Aged; D000428:Alcohol Drinking; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000503:physiopathology / Q000517:prevention & control*; D016022:Case-Control Studies; D015331:Cohort Studies; D016001:Confidence Intervals; D000431:Ethanol / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011322:Primary Prevention / Q000379:methods*; D012217:Rheumatoid Factor / Q000276:immunology
chemical_list: D000431:Ethanol; D012217:Rheumatoid Factor