Epidemiological and clinical characteristics of myasthenia gravis in Belgrade, Yugoslavia (1983-1992)

This is the first epidemiological study of myasthenia gravis (MG) in the ar ea of Belgrade. During the survey period (1983-1992), 124 incidental cases of MG were observed, producing an average annual incidence rate of 7.1 per million population (women, 8.3; men, 5.8). Age and sex specific incidence r ates for females demonstrated a bimodal pattern, with the first peak in the age group between 20 and 40, and the second peak in the age group 70-80. T he age-specific rates for males showed unimodal pattern, reaching a maximum in the age group between 60 and 80. There was a tendency of more frequent disease appearance in the urban as opposed to the suburban districts. On th e prevalence day, December 31, 1992, the point prevalence rate was 121.5 pe r million (women, 142.5; men, 98.8). Only for incidental cases, the point p revalence rate was 77.1 (women, 83.2; men, 70.4). The average annual mortal ity rate was 0.47 per million (females, 0.52; males, 0.42), while cumulativ e lethality was 5.6 (women, 5.6; men, 5.7). Most frequently initial symptom s were ocular, occurring in 58% patients. Through the period of investigati on ocular symptoms were generalized in 68%, most frequently in the first 2 years (62.5%). Thymoma was confirmed in 11.3% of patients. In this group th ere was equal presence of both sexes, older median age at onset, and more s evere clinical course of MG. Associated autoimmune disease was found in 17 out of 124 incidental cases (13.7%). The most common were thyroid diseases (7.3%). Family history of MG was recorded in 2 cases belonging to 1 family (1.6%).