Smoking and socio-economic status may affect myasthenia gravis

Eur J Neurol. 2013 Mar;20(3):453-460. doi: 10.1111/j.1468-1331.2012.03843.x. Epub 2012 Aug 31.


Background and purpose: The influence of environmental factors in myasthenia gravis (MG) is unknown. The aim of this cross-sectional population-based study was to investigate if smoking and socio-economic status (SES) were associated with MG in the Norwegian population.

Methods: Subjects were 491 MG patients identified in Norway at the time of the study (point prevalence 12.7/100 000). A questionnaire covering smoking habits and markers of SES (education and occupation) was mailed to all patients. Population data were obtained from Statistics Norway.

Results: A total of 375 (76.6%) patients completed the questionnaire (236 women, mean age 59 ± 18 years), of which 193 reported to be early onset MG (EOMG, onset ≤40 years, 155 women). Compared with the general population, current smoking was more prevalent amongst MG patients [risk ratio (RR) 1.5; 95% confidence interval (CI) 1.1-1.9], most of whom had EOMG. Female MG patients had higher education compared with the general population (RR 4.5; 95% CI 3.2-6.2). Male MG patients were similar to the general population regarding both education and occupation, except for a subset of late onset MG who had shorter education (RR 1.9; 95% CI 1.1-3.2) and had worked in crafts and related trades. About half of working age MG patients received disability pension, a finding significantly related to low educational level and a more severe disease course (P < 0.001).

Conclusion: This is the first report indicating that smoking and SES may affect MG. Further studies investigating their role as potential risk factors are warranted.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age of Onset
  • Aged
  • Cross-Sectional Studies
  • Female
  • Humans
  • Male
  • Middle Aged
  • Myasthenia Gravis / epidemiology*
  • Myasthenia Gravis / etiology
  • Norway / epidemiology
  • Prevalence
  • Smoking / adverse effects*
  • Smoking / epidemiology*
  • Social Class*
  • Young Adult