Mortality rates and causes of death in Swedish Myasthenia Gravis patients

Myasthenia Gravis (MG) is an autoimmune disease with several comorbidities, however information on MG mortality remains sparse. We conducted a nationwide register-based study on mortality rates and causes of death among Swedish MG patients. Data was acquired from four Swedish National Board of Health and Welfare registers. A total of 4559 MG patients (2522 women, 55.3%) being alive entering the year 2006, were identified. 1121 patients (562 women, 50.1%) died during 2006-2016. Age- and gender-standardized mortality rate was 1.51 (95% CI 0.40) per 100 patients and did not differ from the Swedish general population. Time from MG diagnosis to death was 8.9 ± 6.8 years. The most common ultimate cause of death was cancer (19.5%), followed by ischemic heart disease (13.3%) and MG (11.3%). When MG was stated as the ultimate cause of death, there was a strikingly higher likelihood of having influenza/pneumonia as a contributing cause of death (OR 2.5, p<0.0001). In conclusion, although we could not confirm a higher mortality rate in Swedish MG patients compared to the general population, and despite modern advancements in treatment, we observed that MG itself was stated as the third most common ultimate cause of death in Swedish MG patients.