title: The increasing prevalence of multiple sclerosis in New Zealand.
abstract: BACKGROUND
  New Zealand (NZ) has a high prevalence of multiple sclerosis (MS). Worldwide, the prevalence of MS appears to be increasing.
  
  
  OBJECTIVE
  To review all published prevalence studies undertaken in NZ to determine whether the prevalence of MS in NZ is increasing.
  
  
  METHODS
  PubMed, Medline, Scopus, Web of Knowledge, EMBASE, AMED and CINAHL were searched to identify studies reporting the prevalence of MS in NZ. Prevalence rates from the National MS Prevalence study in 2006 were compared with earlier prevalence rates for the same regions using Poisson regression.
  
  
  RESULTS
  Prevalence rates reported in the earlier regional studies ranged from 23.6 to 68.5/100,000 population; in the same regions in 2006, the range was 47.6-134.2/100,000 population. Prevalence rates were significantly increased in all regions studied except for the Bay of Plenty. The increase in prevalence was seen in both sexes. The sex ratio remained constant over time.
  
  
  CONCLUSIONS
  In studies spanning almost 40 years (1968-2006), the prevalence of MS within the same regions of NZ has significantly increased whereas the sex ratio and latitudinal gradient have remained stable.
authors.affiliation: New Zealand Brain Research Institute, Christchurch, New Zealand.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Alla
authors.forename: John
authors.initials: J
authors.lastname: Pearson
authors.forename: Laëtitia
authors.initials: L
authors.lastname: Debernard
authors.forename: David
authors.initials: D
authors.lastname: Miller
authors.forename: Deborah
authors.initials: D
authors.lastname: Mason
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000453:epidemiology*; D009520:New Zealand / Q000453:epidemiology; D015995:Prevalence