Myasthenia gravis and elderly people.

Myasthenia gravis is probably commoner than previously suspected, the annual incidence being nearer 9-10/million than earlier figures of 2-4/million. The current study found an annual incidence in Croyden of 9.1 per million (95% confidence limits 5.7-13.8 per million). Of the 22 patients (59%) seen in Croyden with newly diagnosed myasthenia gravis during the past 7 years, 13 were aged over 60. In a separate study of the age distribution of positive acetylcholine receptor antibody assays, 51% were 60 years or above in 1991, and 64% in 1994. The peak age in both sexes was 70-80, and numbers were greatest in men aged 60-80.