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

Abstract

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.