Prevalence of Multiple Sclerosis in Iceland.

Background: In this study, we examined multiple sclerosis (MS) point prevalence in the well-defined island population of Iceland.

Methods: This study included all registered residents of Iceland with MS on the prevalence day, December 31, 2007. All included patients met at least one of the following criteria: McDonald criteria; Poser criteria for clinically definite MS, laboratory-supported definite MS, clinically probable MS; or criteria for primary progressive MS. The patients' medical records were reviewed, including all available MRI data acquired prior to the prevalence day.

Results: We identified 526 patients, of whom 73% (382) were women. The crude point prevalence of MS was 167.1 per 100,000 population on the prevalence day. With age adjustment made to the 2000 U.S. population, the prevalence was 166.5 per 100,000 population. The mean patient age on the prevalence day was 47 years(range 13-89) for both men and women. The mean age at diagnosis was 36 years (range 13-77): 35 years for women and 36 years for men.

Conclusion: MS prevalence was high in Iceland compared to the prevalence mentioned in reports from most of the world, and was similar to prevalence rates in other Nordic countries.