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

Abstract

This is the first epidemiological study of myasthenia gravis (MG) in the area 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 rates 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. The 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 the prevalence day, December 31, 1992, the point prevalence rate was 121.5 per million (women, 142.5; men, 98.8). Only for incidental cases, the point prevalence rate was 77.1 (women, 83.2; men, 70.4). The average annual mortality rate was 0.47 per million (females, 0.52; males, 0.42), while cumulative lethality was 5.6 (women, 5.6; men, 5.7). Most frequently initial symptoms were ocular, occurring in 58% patients. Through the period of investigation 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 there was equal presence of both sexes, older median age at onset, and more severe 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%).

Myasthenia gravis in Ceará, Brazil: clinical and epidemiological aspects

“…Patients with thymoma had an older age of onset of symptoms, but there were no gender differences. These data are similar to those reported by Lavrnic et al 30 .…”

Geographical Distribution of Myasthenia Gravis in Northern Europe - Results from a Population-Based Study from Two Countries

“…The studied area in the Netherlands is characterized by a high population density and urbanity, with large cities and an airport. Two recent studies examining the geographical variation have found more prevalent MG cases in the urban areas compared to the rural areas [2,45] . One could speculate whether the urban differences reflect individual behavior or exposure of exogenous environmental factors like, for example, air pollution influencing the disease development.…”

The Incidence of Myasthenia Gravis: A Systematic Literature Review

“…Ten investigations used census or other national statistics data for their denominator [21,22,24,27,29,31,36,39,40,43] , one did not give any denominator data [13] and the others provided denominator estimates but did not give their source. Overestimation of incidence rates was thought to be unlikely where specialists diagnosed or reviewed the cases included [14, 16, 18, 19, 24-27, 29, 32, 36, 37] ; other studies reported reliable case identification [40] , using a 3-year follow-up period to ensure correct diagnosis [23] and a regular clinical follow-up to exclude questionable cases [13] .…”

“…The main causes of missing cases in the studies were mild symptoms or cases being diagnosed and managed in primary care but the case finding strategy of the incidence study only including secondary care records [16-18, 20-25, 27, 30, 37, 40, 41] , death before a diagnosis was made [17,21,22,27,42] and misdiagnosis [36,42] [21,38,40] only included patients who were seropositive for antiAChR antibodies, which will have underestimated the incidence rates by about 15% [1,4,40] . Ten investigations used census or other national statistics data for their denominator [21,22,24,27,29,31,36,39,40,43] , one did not give any denominator data [13] and the others provided denominator estimates but did not give their source.…”