title: Aetiological factors of importance for the development of rheumatoid arthritis.
abstract: OBJECTIVE
  To evaluate exposure to external factors associated with risk or prevention of rheumatoid arthritis (RA).
  
  
  METHODS
  Two hundred and ninety-three incident cases of RA and 1346 population-based referents were included in a case-referent study, in which previous exposure experiences were collected through a postal questionnaire.
  
  
  RESULTS
  An inverse association between RA and additional schooling after compulsory school was seen for men. Current smoking was associated with significantly increased risks of RA for men and women [odds ratio (OR) 2.9, 95% confidence interval (CI) 1.4-6.4, and OR 1.8, 95% CI 1.1-2.9, respectively], as was previous smoking for men (OR 2.3, 95% CI 1.2-4.4). There were also indications of relationships between previous use of a private well and RA in both men and women.
  
  
  CONCLUSIONS
  Several previously published associations have been reproduced in the present study, which also generates some new hypotheses that suggest further research.
authors.affiliation: Division of Occupational and Environmental Medicine, Unit for Autoimmunity and Immune Regulation, Department of Molecular and Clinical Medicine, Linköping University, Sweden. asa.reckner.olsson@lio.se
authors.forename: A Reckner
authors.initials: AR
authors.lastname: Olsson
authors.forename: T
authors.initials: T
authors.lastname: Skogh
authors.forename: G
authors.initials: G
authors.lastname: Wingren
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000453:epidemiology / Q000209:etiology*; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D008593:Menopause; D008875:Middle Aged; D012016:Reference Values; D012307:Risk Factors; D012907:Smoking; D011795:Surveys and Questionnaires