Tobacco Use Is Associated with Greater Disability in Multiple Sclerosis

Tobacco smoking is a permissive factor in the development of multiple sclerosis (MS), but the impact on the clinical course has not been established (NEJM JW Neurol Aug 3 2005). Investigators used data from a region-based U.K. MS clinic that included 895 complete cases with a median 15 years of follow-up. Study covariates included age at first clinical manifestation of disease, disease subtypes (e.g., relapsing or progressive), and treatment duration <1 year or ≥1 year. Smoking status was assessed during the clinic visit associated with the first clinical event and categorized as nonsmoker, ex-smoker, or current smoker.

Using the MS Severity Score, those who ever smoked were significantly more likely to be in the most severely disabled quartile of this scale (57% ever-smokers vs. 35% never-smokers). Compared with never-smokers, ever-smokers were 34% more likely to develop moderate disability in at least one system (Expanded Disability Status Scale score [EDSS] of 4.0) and 25% more likely to progress to require use of a cane to ambulate (EDSS = 6.0). Ex-smokers had a lower risk for disability than current smokers, a 35% reduction in risk for reaching EDSS 4.0, and a 31% reduction in risk for reaching EDSS 6.0.