Follow-up study on amyotrophic lateral sclerosis in Rochester, Minn., 1925 through 1984.

The incidence, secular trend and survivorship of amyotrophic lateral sclerosis in the Rochester, Minn., population has been investigated over a 60-year period, 1925 through 1984. The crude average annual incidence rate was 2.0 per 100,000 population. The rate, age- and sex-adjusted to the US 1970 white population, was 2.4 per 100,000 population (3.0 for men and 2.0 for women), with a male to female ratio of 1.5:1. Incidence rates after 1955 showed a small but nonsignificant increase compared to those of the former 30-year period. Median age at onset was 67.5 years; the incidence rates increased significantly with advancing age, but without a peak. Median survivorship was 23.8 months, and younger patients had a better prognosis than patients with an advanced age at onset. No change in duration of survivorship was observed over the period studied. Two of the 44 patients (4.5%) had a family history of amyotrophic lateral sclerosis.