Epidemiology of Myasthenia Gravis in Sweden 2006-2016

Introduction Reported incidence and prevalence rates of Myasthenia Gravis (MG) vary widely and are assumed to have increased over the last few decades. We conducted a nationwide register-based study on the current incidence and prevalence of MG and MG subgroups in Sweden. Methods Data were acquired from four Swedish Health Registers in order to identify patients with MG. Incidence and prevalence rates were calculated for the years 2006-2016, using population numbers provided by Statistics Sweden. Results In 2016, the incidence of MG in Sweden was 2.9 per 100,000 inhabitants (95% CI: 2.5-3.2/100,000) and the crude prevalence was 36.1 per 100,000 inhabitants (95% CI: 34.9-37.3). There was a significant increase in Myasthenia Gravis prevalence from 2006 to 2016. Prevalence rates of all MG subgroups but thymoma-associated MG increased over the same period of time. Conclusions The incidence and prevalence of Myasthenia Gravis have increased over time in Sweden, and the rates are high in comparison with other countries.