MS prevalence in New Zealand, an ethnically and latitudinally diverse country
Taylor, BV and Pearson, JF and Clarke, G and Mason, DF and Abernethy, DA and Willoughby, E and Sabel, C, MS prevalence in New Zealand, an ethnically and latitudinally diverse country , Multiple Sclerosis, 16, (12) pp. 1422-1431. ISSN 1352-4585 (2010) [Refereed Article]
Background: The prevalence of multiple sclerosis (MS) is not uniform, with a latitudinal gradient of prevalence present
in most studies. Understanding the drivers of this gradient may allow a better understanding of the environmental factors
involved in MS pathogenesis.
Method: The New Zealand national MS prevalence study (NZMSPS) is a cross-sectional study of people with definite MS
(DMS) (McDonald criteria 2005) resident in New Zealand on census night, 7 March 2006, utilizing multiple sources of
notification. Capture–recapture analysis (CRA) was used to estimate missing cases.
Results: Of 2917 people with DMS identified, the crude prevalence was 72.4 per 100,000 population, and 73.1 per
100,000 when age-standardized to the European population. CRA estimated that 96.7% of cases were identified. A
latitudinal gradient was seen with MS prevalence increasing three-fold from the North (35S) to the South (48S). The
gradient was non-uniform; females with relapsing–remitting/secondary-progressive (RRMS/SPMS) disease have a gradient
11 times greater than males with primary-progressive MS (p<1107). DMS was significantly less common among
those of Maori ethnicity.
Conclusions: This study confirms the presence of a robust latitudinal gradient of MS prevalence in New Zealand. This
gradient is largely driven by European females with the RRMS/SPMS phenotype. These results indicate that the environmental
factors that underlie the latitudinal gradient act differentially by gender, ethnicity and MS phenotype. A better
understanding of these factors may allow more targeted MS therapies aimed at modifiable environmental triggers at the