title: Level of education and multiple sclerosis risk over a 50-year period: Registry-based sibling study.
abstract: BACKGROUND
  The conflicting results from studies on socioeconomic status (SES) and multiple sclerosis (MS) risk might be due to a change in the distribution of environmental exposures over time or to methodological limitations in previous research.
  
  
  OBJECTIVE
  To examine the association between SES and MS risk during 50 years.
  
  
  METHODS
  We included patients registered in Norwegian MS registries and prevalence studies born between 1930 and 1979, and identified their siblings and parents using the Norwegian Population Registry. Information on education was retrieved from the National Education Registry, categorized into four levels (primary, secondary, undergraduate and graduate) and compared in patients and siblings using conditional logistic regression.
  
  
  RESULTS
  A total of 4494 MS patients and 9193 of their siblings were included in the analyses. Level of education was inversely associated with MS risk ( p trend < 0.001) with an odds ratio (OR) of 0.73 (95% confidence interval (CI): 0.59-0.90) when comparing the highest and lowest levels. The effect estimates did not vary markedly between participants born before or after the median year of birth (1958), but we observed a significant effect modification by parental education ( p = 0.047).
  
  
  CONCLUSIONS
  Level of education was inversely associated with MS risk, and the estimates were similar in the earliest and latest birth cohorts.
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway/The Norwegian Multiple Sclerosis Competence Center, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Kjetil
authors.initials: K
authors.lastname: Bjørnevik
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway/The Norwegian Multiple Sclerosis Competence Center, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Trond
authors.initials: T
authors.lastname: Riise
authors.affiliation: Department of Neurology, Nordland Hospital Trust, Bodø, Norway.
authors.forename: Espen
authors.initials: E
authors.lastname: Benjaminsen
authors.affiliation: Department of Neurology, Oslo University Hospital, Ullevål, Oslo, Norway/Institute of Health and Society, Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Elisabeth G
authors.initials: EG
authors.lastname: Celius
authors.affiliation: Department of Neurology, Namsos Hospital, Namsos, Norway.
authors.forename: Ole P
authors.initials: OP
authors.lastname: Dahl
authors.affiliation: Department of Neurology, University Hospital of North Norway, Tromsø, Norway.
authors.forename: Margitta T
authors.initials: MT
authors.lastname: Kampman
authors.affiliation: Innlandet Hospital Trust, Lillehammer, Norway.
authors.forename: Kristin I
authors.initials: KI
authors.lastname: Løken-Amsrud
authors.affiliation: Molde Hospital, Molde, Norway/Unit for Applied Clinical Research, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Rune
authors.initials: R
authors.lastname: Midgard
authors.affiliation: The Kristian Gerhard Jebsen Centre for MS Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway/The Norwegian Multiple Sclerosis Registry and Biobank, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Kjell-Morten
authors.initials: KM
authors.lastname: Myhr
authors.affiliation: The Norwegian Multiple Sclerosis Competence Center, Department of Neurology, Haukeland University Hospital, Bergen, Norway/The Kristian Gerhard Jebsen Centre for MS Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway.
authors.forename: Øivind
authors.initials: Ø
authors.lastname: Torkildsen
authors.affiliation: Department of Neurology, Sørlandet Hospital Kristiansand, Kristiansand, Norway.
authors.forename: Anita
authors.initials: A
authors.lastname: Vatne
authors.affiliation: The Norwegian Multiple Sclerosis Competence Center, Department of Neurology, Haukeland University Hospital, Bergen, Norway/The Kristian Gerhard Jebsen Centre for MS Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway.
authors.forename: Nina
authors.initials: N
authors.lastname: Grytten
mesh_terms: D000328:Adult; D000368:Aged; D004522:Educational Status; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology*; D016017:Odds Ratio; D012042:Registries / Q000706:statistics & numerical data; D012307:Risk Factors; D035781:Siblings; D012923:Social Class
keywords: Multiple sclerosis; education; environmental risk factors; epidemiology; risk factors; socioeconomic status