title: The prevalence and clinical characteristics of MS in northern Japan.
abstract: In Japan, there is a low prevalence rate (PR) of multiple sclerosis (MS; 0.8-4.0/100,000) but a relatively high frequency of "optic-spinal form" MS (OS-MS). There have been no intensive epidemiologic frequency studies, however, in over 30 years. We performed a province-wide prevalence study of MS in the Tokachi province of Hokkaido, the northernmost island of Japan, and compared the observed clinical features with other populations in Japan and Western countries. Prevalence was determined on March 31, 2001. The primary sources for the case ascertainment were 13 hospitals that treated patients with neurologic diseases including MS in Tokachi. Patients were classified according to Poser's criteria. The prevalence rate of clinically definite or laboratory-supported definite MS (LSDMS) was 8.57 per 100,000 [31/361,726; male/female ratio=1:2.9, and age at onset=29.1+/-14.2 (mean+/-SD) years]. Out of the 31 patients, 5 (16%) were classified as OS-MS. The prevalence rate of MS in the Tokachi province was the highest reported in Orientals to date, although still low in comparison with Western communities at a similar latitude. In contrast to the previous reports in Japan, there was a relatively low frequency of OS-MS in Hokkaido.
authors.affiliation: Department of Neurology, Obihiro Kosei General Hospital, Obihiro, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Houzen
authors.forename: Masaaki
authors.initials: M
authors.lastname: Niino
authors.forename: Seiji
authors.initials: S
authors.lastname: Kikuchi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Fukazawa
authors.forename: Shinji
authors.initials: S
authors.lastname: Nogoshi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Kunio
authors.initials: K
authors.lastname: Tashiro
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001927:Brain Diseases / Q000150:complications / Q000175:diagnosis; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000145:classification / Q000453:epidemiology* / Q000503:physiopathology*; D015995:Prevalence; D017678:Sex Distribution