Epidemiological study of adult-onset myasthenia gravis in the area of Belgrade (Serbia) in the period 1979-2008.

ABSTRACT

BACKGROUND: The aim of this study was to analyze the prevalence and incidence of adult-onset myasthenia gravis (MG) in the Belgrade population from 1979 to 2008. METHODS: Data on the number of MG patients and their basic demographic and clinical characteristics were collected from hospital records (1979-1992) and the Belgrade MG Registry (1993-2008). Incidence and prevalence were standardized by the direct method (using the world standard population). A time-trend analysis of MG incidence was performed using a linear regression model. RESULTS: During the study period 562 cases (316 women, 246 men) were registered. On December 31st, 2008, the standardized prevalence (according to the world standard population) was 188.3/1,000,000 (women 237.8/1,000,000; men 139.4/1,000,000). The average annual standardized incidence rate was 13.3/1,000,000 (women 14.1/1,000,000; men 12.2/1,000,000). The incidence rates tended to increase significantly in both sexes during the study period (y = 3.299 + 14.363x, p = 0.002). Age-specific incidence rates for women demonstrated a bimodal pattern, with the first peak in the 20- to 29-year age group and the second one in the ≥70-year group. For both genders, an increase in age-specific incidence rates was registered for all age groups, although this was significant (p = 0.001) only for an MG onset of ≥60 years of age. CONCLUSIONS: The study confirms an increase in the incidence of MG in the area of Belgrade during the study period, especially for those with MG onset after 60 years of age.