title: Association of smoking with amyotrophic lateral sclerosis risk and survival in men and women: a prospective study.
abstract: BACKGROUND
  Previous epidemiologic studies have examined the association of smoking with amyotrophic lateral sclerosis (ALS) incidence, but their results have been inconsistent. Moreover, limited information exists on the association between smoking and survival in ALS patients. We evaluated the association of smoking with ALS incidence and survival in a population-based cohort.
  
  
  METHODS
  We conducted a case-control study nested in the General Practice Research Database, a computerized clinical database in the United Kingdom. Cases were 1143 individuals with a diagnosis of ALS; 11,371 matched controls were selected among GPRD participants free of ALS. Predictors of survival were determined in the ALS cases. Smoking information was obtained from the computer database.
  
  
  RESULTS
  Smoking was not associated with the risk of ALS in this population. The rate ratio (RR) of ALS comparing ever versus never smokers was 1.04, 95% confidence interval (CI) 0.80-1.34. In analysis stratified by gender, however, ever smoking was associated with ALS in women (RR 1.53, 95% CI 1.04-2.23) but not in men (RR 0.75, 95% CI 0.53-1.06). Mortality was 71% after 2.1 average years of follow-up. Old age and female sex were associated with lower survival. Smoking was a predictor of mortality only in women. Comparing ever versus never smokers, RR (95% CI) of death was 1.31 (1.04-1.65) in women, and 0.90 (0.72-1.11) in men.
  
  
  CONCLUSIONS
  In this large population-based study, smoking was associated with ALS risk and worse survival in women but not in men.
authors.affiliation: Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN, USA. aalogut@alumni.unav.es
authors.forename: Alvaro
authors.initials: A
authors.lastname: Alonso
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Logroscino
authors.forename: Susan S
authors.initials: SS
authors.lastname: Jick
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Hernán
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology* / Q000401:mortality*; D016022:Case-Control Studies; D015331:Cohort Studies; D003201:Computers; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology*; D006113:United Kingdom; D055815:Young Adult