The Increasing Prevalence of Multiple Sclerosis in New Zealand

Background: New Zealand (NZ) has a high prevalence of multiple sclerosis (MS). Worldwide, the prevalence of MS appears to be increasing. Objectives: 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. (C) 2014 S. Karger AG, Basel