title: Smoking increases the risk of progression in multiple sclerosis: A cohort study in Queensland, Australia.
abstract: BACKGROUND
  Cigarette smoking has been associated with increased risk of progressive multiple sclerosis (MS). The effect of smoking status on risk and timing of disease progression in patients with MS in Queensland, Australia has not been established.
  
  
  METHODS
  A clinical cohort of 646 cases (531 females, 115 males) were followed from first clinic attendance to onset of clinically determined progressive disease. Progression risk was analysed with gender, age, age of onset, exposure to disease modifying therapy, and smoking status as covariates in a Cox proportional hazards analysis.
  
  
  RESULTS
  There were significantly higher risks of secondary progressive disease in males (Hazard Ratio, HR 1.83, 95% CI: 1.3-2.7) and in ever smokers (HR 1.4, 95% CI: 1.0-2.0). Progressive disease occurred approximately 4years earlier in ever smokers. Smoking did not affect age of onset of primary progressive disease.
  
  
  CONCLUSIONS
  Cigarette smoking was associated with earlier onset of progressive disease in this large clinical cohort. For patients with relapsing-remitting disease, smoking cessation should be encouraged.
authors: School of Medicine, Gold Coast Campus, Griffith University, Gold Coast, QLD 4222, Australia. Electronic address: c.ogorman@griffith.edu.au.
authors: Cullen M
authors: CM
authors: O'Gorman
authors: School of Medicine, Gold Coast Campus, Griffith University, Gold Coast, QLD 4222, Australia.
authors: Simon A
authors: SA
authors: Broadley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology* / Q000503:physiopathology*; D015995:Prevalence; D016016:Proportional Hazards Models; D011793:Queensland / Q000453:epidemiology; D012306:Risk; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology* / Q000503:physiopathology*; D055815:Young Adult
keywords: Epidemiology; Multiple sclerosis progression; Relapsing-remitting multiple sclerosis; Smoking; Survival analysis