Myasthenia gravis epidemiology : from environmental risk factors to quality of life

Abstract

Myasthenia gravis is an autoimmune disease associated with a variable degree of muscular weakness and fatigability. Over the past decades, several studies have found increasing incidence rates, especially among men and higher age groups, although the underlying reasons are unknown. On the other hand, mortality rates have changed dramatically over the past century so that MG patients now have almost the same life expectancy as people free of MG. However, it is not known to what degree this is also paralleled by a similar improvement in quality of life among people living with MG. The objective of this PhD thesis was to explore both possible environmental risk factors impacting MG risk, as well as to determine how residual disease symptoms correlate with quality of life scores by using questionnaire and registry data.In study I we described the Genes and Environment in MG (GEMG) - study population. We estimated that almost half the patients at inclusion had an unacceptable symptom state indicating an unmet need of improved disease control.In study II we used the nationwide MG registry to assess how disease activity and quality of life measurements covaried. We concluded that at already low disease activity patients reported significantly decreased quality of life indicating a need for improved treatment algorithms or treatments.In study III we explored the impact of smoking, snuff use and alcohol consumption on MG disease risk using the GEMG questionnaire. We found that, alcohol consumption was negatively associated with developing MG in all subgroups. Further smoking or snuff use at onset was positively associated with developing early onset MG. In study IV we explored the impact of body mass index (BMI), physical activity and fish consumption on MG disease risk using the GEMG questionnaire. We found that BMI significantly impacted the risk of MG. When estimating population attributable fraction, we found a specifically high impact in male patients, which we hypothesize could explain part of the observed incidence increase. Physical activity was not associated with MG, while at least weekly fish consumption at age 20 was associated with a decreased risk of MG.List of scientific papersI. Petersson M, Feresiadou A, Jons D, Ilinca A, Lundin F, Johansson R, Budzianowska A, Roos AK, Kågström V, Gunnarsson M, Sundström P, Piehl F, Brauner S. Patient-Reported Symptom Severity in a Nationwide Myasthenia Gravis Cohort: Cross- sectional Analysis of the Swedish GEMG Study. Neurology, 2021. PMID: 34376512. https://doi.org/10.1212/wnl.0000000000012604II. Petersson M, Wu J, Berggren F, Schager I, Piehl F, Brauner S. Impact of disease activity on quality of life and EQ-5D-3L score in myasthenia gravis: results from the Swedish MG registry. Journal of Neurology, 2025. PMID: 40775536. https://doi.org/10.1007/s00415-025-13298-4III. Petersson M, Jons D, Feresiadou A, Ilinca A, Lundin F, Johansson R, Budzianowska A, Roos AK, Kågström V, Gunnarsson M, Sundström P, Klareskog L, Olsson T, Kockum I, Piehl F, Alfredsson L, Brauner S. Nicotine, Alcohol Consumption, and Risk of Myasthenia Gravis: Results From the Swedish Nationwide GEMG Study. Neurology, 2025. PMID: 40493875. https://doi.org/10.1212/wnl.0000000000213771IV. Petersson M, Ilinca A, Jons D, Feresiadou A, Lundin F, Johansson R, Budzianowska A, Roos AK, Kågström V, Gunnarsson M, Sundström P, Kockum I, Klareskog L, Olsson T, Piehl F, Alfredsson L, Brauner S. Body mass index, physical activity, fish consumption and association to Myasthenia gravis: Results from the Swedish GEMG-study. [Submitted]</p