INCIDENCE AND PREVALENCE OF MYASTHENIA-GRAVIS IN WESTERN DENMARK - 1975 TO 1989

We studied the epidemiology of myasthenia gravis (MG) in western Denma rk from 1975 to 1989, basing case identification on records from all h ospitals in the survey area. The population surveyed was 2.80 million in 1985. The average annual incidence rate was 5.0 per million populat ion (women, 5.9; men, 4.2). The point-prevalence rate (January 1, 1990 ) was 78 per million population (women, 102; men, 53). In men, the inc idence increased after 40 years. In women, the incidence rates showed a bimodal pattern with a peak of 7.0 in the age group 20 to 29 years a nd a second peak of 11.7 in the age group 70 to 79 years. The differen ces in sex- and age-specific incidence rates suggest that younger wome n are more susceptible to MG than younger men. Old men and postmenopau sal women had similar rates. When last examined, 21% of the 220 preval ent cases were in remission and 18%. were moderately or severely disab led.