RT Journal Article SR Electronic T1 Smoking and the risk of amyotrophic lateral sclerosis: a systematic review and meta-analysis JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 1249 OP 1252 DO 10.1136/jnnp.2009.180232 VO 81 IS 11 A1 Alvaro Alonso A1 Giancarlo Logroscino A1 Miguel A HernĂ¡n YR 2010 UL http://jnnp.bmj.com/content/81/11/1249.abstract AB Background Epidemiologic studies have provided inconsistent results on the association of cigarette smoking with the incidence of amyotrophic lateral sclerosis (ALS). To summarise published evidence and explore sources of heterogeneity, we conducted a systematic review and meta-analysis of studies that evaluated this association.Methods Published studies evaluating the association of smoking with incidence of ALS were searched in bibliographic databases, with relevant information collected from each article. A random effects approach was used to pool the relative rate (RR) estimates from different studies. Between study heterogeneity was explored with a meta-regression approach.Results 18 publications reported associations between smoking and ALS risk in 15 case control studies and five cohort studies. The pooled RR (95% CI) of ALS was 1.28 (0.97 to 1.68) for current versus never smokers and 1.12 (0.98 to 1.27) for ever versus never smokers. The study specifics RRs were heterogeneous (p<0.01). The proportion of women in the study population explained 46% of between study variability. The estimated RR (95% CI) of ALS for ever versus never smokers was 0.86 (0.71 to 1.03) in men and 1.66 (1.31 to 2.10) in women.Interpretation This meta-analysis does not support an overall strong association of smoking with ALS risk but suggests that smoking might be associated with a higher risk of ALS in women.