Further considerations on the distribution of multiple sclerosis in Sweden

Abstract

The geographic distribution of multiple sclerosis (MS) in Sweden over time was compared in order to analyze homogeneity. The distribution of MS was compared among three nationwide resources: 1301 hospital cases 1925-1934; 5425 deaths 1952-1992; and 11,371 disability pension recipients 1971-1994. Distributions by county (lan) were markedly non-homogenous, with greatest variations in the early prevalence series (16-232% of the national mean), less within the death data (75-170%), and least for the disability series (87-128%). Maximal rates for MS in the early prevalence series were found for the cluster of seven counties surrounding the two major lakes of south central Sweden, as well as for one region on the northern shore of the Bay of Bothnia, and another also off the Bay north of Stockholm. Though the epidemiologic sources are quite different, they are internally consistent and thus provide three consecutive cross-sectional views of the distribution over time. When considered together the data may be compatible with a thesis of the origin and spread of MS within Sweden from the south-central inland lake regions of the country. Such spread within a half century is too rapid for a genetic cause, including HLA patterns.