title: Assessing possible selection bias in a national voluntary MS longitudinal study in Australia.
abstract: BACKGROUND
  Surveying volunteer members of a multiple sclerosis registry is a very cost-effective way of assessing the impact of the disease on life outcomes. However, whether the data from such a study can be generalised to the whole population of persons living with MS in a country or region is unclear.
  
  
  METHODS
  Here we compare the demographic and disease characteristics of participants in one such study, the Australian Multiple Sclerosis Longitudinal Study (AMSLS), with two well-characterised MS prevalence studies with near-complete ascertainment of MS in their study regions.
  
  
  RESULTS
  Although some differences were found, these largely represented the effects of geography (sex ratios) and local factors (national immunomodulatory therapy prescribing requirements), and the cohorts were otherwise comparable. Overall, despite comprising only 12-16% of MS cases in Australia, the AMSLS is highly representative of the MS population.
  
  
  CONCLUSIONS
  Therefore with some minor caveats, the AMSLS data can be generalised to the whole Australasian MS population. Volunteer disease registries such as this can be highly representative and provide an excellent convenience sample when studying rare conditions such as MS.
authors.affiliation: Menzies Research Institute Tasmania, University of Tasmania, Hobart, Australia.
authors.forename: Bruce V
authors.initials: BV
authors.lastname: Taylor
authors.forename: Andrew
authors.initials: A
authors.lastname: Palmer
authors.forename: Steve
authors.initials: S
authors.lastname: Simpson
authors.forename: Robyn
authors.initials: R
authors.lastname: Lucas
authors.forename: Rex D
authors.initials: RD
authors.lastname: Simmons
authors.forename: Deborah
authors.initials: D
authors.lastname: Mason
authors.forename: John
authors.initials: J
authors.lastname: Pearson
authors.forename: Glynnis
authors.initials: G
authors.lastname: Clarke
authors.forename: Clive
authors.initials: C
authors.lastname: Sabel
authors.forename: Ernie
authors.initials: E
authors.lastname: Willoughby
authors.forename: Anne
authors.initials: A
authors.lastname: Richardson
authors.forename: David
authors.initials: D
authors.lastname: Abernethy
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005006:Ethnicity; D005260:Female; D006801:Humans; D008137:Longitudinal Studies / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology*; D009520:New Zealand / Q000453:epidemiology; D015995:Prevalence; D012107:Research Design; D015983:Selection Bias; D012737:Sex Factors; D013648:Tasmania / Q000453:epidemiology; D055815:Young Adult
keywords: Outcome measurement; multiple sclerosis; study design