Migration and multiple sclerosis in Alaskan military veterans.

The objective is to provide the first estimates of the prevalence of multiple sclerosis (MS) in Alaskan white males including those migrant to and from the state. A case-control cohort design was utilized with a nationwide series of United States (US) veterans service-connected for MS and matched to pre-illness controls who had entered military service between 1960 and 1994. Among 3,758 white male MS cases and their 7,426 controls were 7 MS and 28 controls resident in Alaska at service entry, who provided an adjusted case/control (C/C) risk ratio for developing MS of 0.47 and an estimated prevalence rate of 22/100,000 population, but only 1 of the 7 had also been born in Alaska, for an estimated prevalence rate of 3.2 per 100,000 (95% confidence interval (CI): 0.08-17.80). The other 6 MS patients and their 26 controls, who migrated from another state to Alaska before onset, had an adjusted C/C ratio of 0.44 for a prevalence rate of 20.6 (95% CI: 7.56-44.90), significantly lower than the reported rate of 45.23 per 100,000 for all US white males in 1976. Another 9 MS patients and 7 controls born in Alaska, who had migrated to another state before entering service, provided an adjusted C/C risk ratio for developing MS of 2.44, with a highly significant elevated prevalence rate of 115 per 100,000 (95% CI: 52.6-218.1). In conclusion, these data suggest that Alaska is not a high-risk area for MS and indicate that migration before onset to Alaska from the high-risk coterminous US decreases the risk of MS and the opposite migration increases it. A formal prevalence survey of MS in Alaska is needed to support or refute these findings.