Epidemiology of multiple sclerosis in US veterans VIII. Long-term survival after onset of multiple sclerosis

Survival to 1996 was analysed for nearly 2500 veterans of World War II who were rated as 'service-connected' for multiple sclerosis as of 1956 by the then Veterans Administration. Survival from onset was defined for all white women and black men, and a random sample of white men. Median survival times from onset were 43 years (white females), 30 years (black males) and 34 years (white males). Crude 50-year survival rates were 31.5% (white females), 21.5% (black males) and 16.6% (white males), but only the white females and white males were significantly different. A proportional hazard analysis was used to identify risk factors for mortality from multiple sclerosis onset year. Significant risk factors included male sex (risk ratio: 1.57), older age at onset (risk ratio: 1.05 per year) and high socioeconomic status (risk ratio: 1.05 per socioeconomic status category). There were no statistically significant differences in survival following multiple sclerosis onset by race or latitude of place of entry into military service, both significant risk factors associated with the development of multiple sclerosis. Standardized mortality ratios utilizing national US data (for 1956-96) showed a marked excess for all three race-sex groups of multiple sclerosis cases, with little difference among them, but with a decreasing excess over time. Relative survival rates, used to compare the survival of multiple sclerosis cases with that of other military veterans, did not differ significantly by sex-race group, nor by latitude of place of entry into military service, but did differ significantly by socioeconomic class. The lack of difference in male and female relative survival rates suggests that the significant difference in survival between male and female multiple sclerosis cases is, at least in part, a result of sex per se and not the disease.