This interesting article investigated the effects of smoking on disability progression and disease severity in 895 people with MS with mean disease duration of 17 years. 49% of participants were regular smokers at the time of diagnosis or disease onset (ever smokers).
They found that the average disease severity as measured by the MS severity scale was greater in ever-smokers, by 0.68. The risk of reaching EDSS scores of 4 and 6 in ever-smokers compared to never-smokers was 1.34 and 1.25 respectively. Current smokers showed 1.64 and 1.49 times higher risk of reaching EDSS scores 4 and 6 compared with non-smokers. Those that stopped smoking either before or after the onset of disease (ex-smokers) had a significantly lower risk of reaching EDSS scores 4 and 6 than current smokers. They did not find any significant difference between ex-smokers and non-smokers in relation to EDSS scores 4 and 6.
Therefore this study demonstrates that regular smoking is associated with more severe disease, in addition to faster progression to disability. A slower progression of disability is seen in smoking cessation whether before or after disease onset.
Authors: Manouchehrinia A, Tench CR
Source: Brain. 2013 Jun 11. [Epub ahead of print]
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