Motor neuron disease in a defined English population: estimates of incidence and mortality.

Linked statistics from hospital records and death certificates were used to study the incidence of and mortality from motor neuron disease in a defined English population. The incidence of motor neuron disease, measured as first-admission rates for the disease, was studied from 1963 to 1985 and death certificates for the patients admitted to hospital were obtained to the end of 1990. The average annual first-admission rate for motor neuron disease was 2.1/100,000 men (95% confidence interval (CI) 1.9 to 2.4) and 1.7/100,000 women (95% CI 1.5 to 1.9). First-admission rates increased with age and peaked in the age range 65-84 years. Motor neuron disease was recorded on the death certificate for 86% of patients who died while they had the disease and there was no appreciable change over time in the recording of motor neuron disease as the underlying cause of death. The admission and mortality data derive from different sources, hospital statistical abstracts and death certificates respectively, but trends over time in the two data sets were similar. There was an increase in mortality during the period covered by the study, as there has been in mortality from motor neuron disease nationally, and the increase in mortality in the Oxford region was accompanied by an increase in first-admission rates. It is concluded that the increase in mortality from motor neuron disease probably occurred as a result of an increase in the diagnosed incidence of the disease rather than changes in death certification practice.