Smoking is a major preventable risk factor for multiple sclerosis

Mult Scler. 2016 Jul;22(8):1021-6. doi: 10.1177/1352458515609794. Epub 2015 Oct 12.


Background: Both smoking and exposure to passive smoking have repeatedly been associated with increased multiple sclerosis (MS) risk, but have never before been studied together. We assessed the public health impact of these factors.

Methods: In a Swedish population-based case-control study (2455 cases, 5336 controls), we calculated odds ratios of developing MS associated with different categories of tobacco smoke exposure, together with 95% confidence intervals, by using logistic regression. The excess proportion of cases attributable to smoking and passive smoking was calculated as a percentage.

Results: Both smoking and exposure to passive smoking contribute to MS risk in a dose-dependent manner. At the population level, 20.4% of all cases were attributable to smoke exposure. Among subjects carrying the genetic risk factor HLA-DRB1*15 but lacking HLA-A*02, 41% of the MS cases were attributable to smoking.

Conclusions: From a public health perspective, the impact of smoking and passive smoking on MS risk is considerable. Preventive measures in order to reduce tobacco smoke exposure are, therefore, essential. In particular, individuals with a history of MS in the family should be informed regarding the impact of smoking on the risk of MS, and the importance of preventing their children from being exposed to passive smoke.

Keywords: Multiple sclerosis; epidemiology; passive smoking; smoking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Female
  • HLA-A2 Antigen / genetics
  • HLA-A2 Antigen / immunology
  • HLA-DRB1 Chains / genetics
  • HLA-DRB1 Chains / immunology
  • Humans
  • Logistic Models
  • Male
  • Middle Aged
  • Multiple Sclerosis / diagnosis
  • Multiple Sclerosis / epidemiology
  • Multiple Sclerosis / genetics
  • Multiple Sclerosis / prevention & control*
  • Odds Ratio
  • Protective Factors
  • Retrospective Studies
  • Risk Assessment
  • Risk Factors
  • Risk Reduction Behavior*
  • Smoking / adverse effects*
  • Smoking / epidemiology
  • Smoking Prevention / methods*
  • Sweden / epidemiology
  • Tobacco Smoke Pollution / adverse effects*
  • Tobacco Smoke Pollution / prevention & control*
  • Young Adult


  • HLA-A*02 antigen
  • HLA-A2 Antigen
  • HLA-DRB1 Chains
  • HLA-DRB1*15 antigen
  • Tobacco Smoke Pollution