The risk of multiple sclerosis in Denmark

Abstract

By means of age specific incidence and death rates for MS, plus age specific death rates all causes, the risk of multiple sclerosis in Denmark has been calculated with a modified life-table method. the cumulative lifetime risk of MS from birth is estimated at 201 per 100,000 (180 in males and 223 in females) - or one chance in 500. the cumulative risk remains about the same from birth until age 25 when it begins to decline toward 0 which is reached at age 60. Period cumulative risks from various ages and for periods ranging from 5 to 30 years were also calculated. Thus, at age 20, the risk of MS within 10 years is 74 per 100,000 and within twenty years, 142, for both sexes combined. With the likely equivalence of the duration of the illness throughout the world, and with little major variation expected for most regions for death rates, all causes, within the ages of concern, we may then estimate the risk of MS for parts of the world considered as high frequency MS (like Denmark), medium frequency (like Italy), or low frequency (like Japan). By applying to these regions the factors of 1.0, 0.3, and 0.04 respectively, as reflecting the ratios of their likely prevalence rates, the cumulative lifetime and period risks may be approximated from the Danish data. Thus in 20 years, a group of 100,000 Japanese migrating to Denmark at age 10 would be expected to contain 4 MS if they retained the low risk of their homeland, as opposed to 92 MS if they acquired the high risk of Denmark.