Incidence and lifetime risk of motor neuron disease in the United Kingdom: a population-based study

To estimate the incidence and lifetime risk of motor neuron disease (MND) in a population-based sample in the United Kingdom. We identified new cases of MND during the period 1990-2005 in the General Practice Research Database, which includes clinical information from more than 3 million Britons enrolled with selected general practitioners. Individuals with a first medical diagnosis of MND recorded in the database were considered incident cases of the disease. The positive predictive value of the computer-based diagnosis was estimated through review of a sample of medical records from potential MND cases. In the period 1990-2005, 830 new cases of MND were identified. Age-standardized incidence of MND was 2.6 per 100 000 persons per year in women (95% CI: 2.3, 2.8) and 3.9 in men (95% CI: 3.6, 4.3). Incidence for both sexes peaked between 75 and 79 years. The rate of MND in men was 54% higher than in women (95% CI: 33%, 77%). The lifetime risk of MND, adjusting for competing causes of death, was 1 in 472 (2.1 per 1000) in women and 1 in 350 (2.9 per 1000) in men. No increase in MND incidence over time was apparent. In this population-based database, we found that MND incidence is higher in men than women, peaking in both sexes between 75 and 79 years.