title: Sunlight exposure and sun sensitivity associated with disability progression in multiple sclerosis.
abstract: BACKGROUND
  Sunlight and vitamin D have been inversely associated with the risk of multiple sclerosis (MS).
  
  
  OBJECTIVE
  We investigated sunlight exposure and sun sensitivity in relation to disability progression in MS.
  
  
  METHODS
  We conducted a survey among persons with MS, registered by the Flemish MS society, Belgium, and stratified data according to relapsing-onset and progressive-onset MS. We used Kaplan-Meier survival and Cox proportional hazard regression analyses with time to Expanded Disability Status Scale (EDSS) 6 as outcome measure. Hazard ratios for the time from onset and from birth were calculated for the potentially predictive variables, adjusting for age at onset, gender and immunomodulatory treatment.
  
  
  RESULTS
  704 (51.3%) of the 1372 respondents had reached EDSS 6. In relapsing-onset MS, respondents reporting equal or higher levels of sun exposure than persons of the same age in the last 10 years had a decreased risk of reaching EDSS 6. In progressive-onset MS, increased sun sensitivity was associated with an increased hazard of reaching EDSS 6.
  
  
  CONCLUSIONS
  The association of higher sun exposure with a better outcome in relapsing-onset MS may be explained by either a protective effect or reverse causality. Mechanisms underlying sun sensitivity might influence progression in progressive-onset MS.
authors.affiliation: National Center For Multiple Sclerosis, Melsbroek, Belgium. marie.dhooghe@ms-centrum.be
authors.forename: M B
authors.initials: MB
authors.lastname: D'hooghe
authors.forename: P
authors.initials: P
authors.lastname: Haentjens
authors.forename: G
authors.initials: G
authors.lastname: Nagels
authors.forename: M
authors.initials: M
authors.lastname: Garmyn
authors.forename: J
authors.initials: J
authors.lastname: De Keyser
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D020528:Multiple Sclerosis, Chronic Progressive / Q000175:diagnosis / Q000503:physiopathology*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000175:diagnosis / Q000503:physiopathology*; D016016:Proportional Hazards Models; D012306:Risk; D012720:Severity of Illness Index; D013472:Sunlight; D011795:Surveys and Questionnaires; D055815:Young Adult