Temporal and geographic variation in United States motor neuron disease mortality, 1969–1998

Abstract

To describe temporal trends of motor neuron disease (MND) mortality in the United States. Variations in MND by demographic variables of sex, age, geography, and race/ethnicity were evaluated to assess the possible explanations for observed trends. Multiple-cause mortality files from the National Center for Health Statistics for the years 1969 through 1998 were searched for all United States death records with codes corresponding to MND. Age-adjusted mortality rates were calculated by sex, race/ethnicity, age, birth cohort, and place of death. Overall MND mortality rates increased from 1.25 per 100,000 to 1.82 per 100,000, representing a 46% increase during the 30-year period. Rates among women increased by 60% and continue to rise. Rates among men rose by 35% during this period but have leveled off in the most recent decade evaluated. Mortality rates among African Americans and Hispanics were approximately 50% lower than rates among non-Hispanic whites. A southeast to northwest gradient was observed when rates were grouped by 12 geographic areas. MND mortality rates per 100,000 (and 95% CI) ranged from 2.22 (1.89 to 2.55) in the Northwest to 1.57 (1.44 to 1.71) in the Southeast. Variations in motor neuron disease (MND) mortality by time, race/ethnicity, sex, and geography were consistent with the hypothesis that environmental exposures, combined with factors of genetic susceptibility, play a role in the development of MND.