Stroke: smoking cessation of more than 2 years decreased risk of a stroke.

Clinical bottom line (level 1b)

  1. Less than 1% of middle aged women had suffered a stroke at 12 years.
  2. Middle-aged women were at decreased risk of stroke at 12 years if they: had never smoked, quit 2 to 4 years ago, 5 to 9 years ago or = 15 years ago.
  3. Middle-aged women were at decreased risk of a subarachnoid haemorrhage at 12 years if they had never smoked or quit = 15 years ago.
  4. Middle-aged women were at decreased risk of an ischaemic stroke at 12 years if they had: never smoked, quit 2 to 4 years age or quit = 15 years ago.
Kawachi et al: Journal of the American Medical Association 1993; 269: 232-236
Expires November 2002

The study

Prospective cohort study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: population-based

117006 patients (aged range 30 to 55 years, 100% female) nurses free of coronary heart disease, stroke and cancer at baseline

Factors studied:
  • never smoked
  • 2-4 years since quitting smoking
  • 5-9 years since quitting
  • = 15 years since quitting
  • never smoked
  • = 15 years since quitting
  • never smoked
  • 2-4 years since quitting
  • = 15 years since quitting




    • Multivariate analysis was performed to adjust for confounding factors.

    100% followed for 12 years
    Outcomes studied:
  • stroke
  • subarachnoid haemorrhage
  • ischaemic stroke
  • cerebral haemorrhage

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    stroke 12 years 448/117006 0.38%
    (0.35% to 0.42%)
    subarachnoid haemorrhage 12 years 108/117006 0.09%
    (0.08% to 0.11%)
    ischaemic stroke 12 years 275/117006 0.24%
    (0.21% to 0.26%)
    cerebral haemorrhage 12 years 53/117006 0.05%
    (0.03% to 0.06%)

    prognostic factor for
    stroke     		time to outcome adjusted RR
    (95% CI)
    never smoked 12 years 0.37
    (0.29 to 0.46)
    2-4 years since quitting smoking 12 years 0.39
    (0.17 to 0.87)
    5-9 years since quitting 12 years 0.41
    (0.20 to 0.82)
    = 15 years since quitting 12 years 0.39
    (0.23 to 0.65)

    prognostic factor for
    subarachnoid haemorrhage     		time to outcome adjusted RR
    (95% CI)
    never smoked 12 years 0.21
    (0.12 to 0.34)
    = 15 years since quitting 12 years 0.36
    (0.13 to 0.97)

    prognostic factor for
    ischaemic stroke     		time to outcome adjusted RR
    (95% CI)
    never smoked 12 years 0.39
    (0.30 to 0.52)
    2-4 years since quitting 12 years 0.21
    (0.04 to 0.96)
    = 15 years since quitting 12 years 0.37
    (0.18 to 0.76)

    Citation

    1. Kawachi I, Colditz GA, Stampfer MJ, et al: Smoking cessation and decreased risk of stroke in women. Journal of the American Medical Association 1993; 269: 232-236
    Search Terms: stroke in Best Evidence
    Contributor: Nick Shenker, November 1999
    Reviewer: Clare Wotton

    Clinical Question.
    Patient women smokers
    Intervention or Exposure cessation of smoking
    Comparison no cessation
    Outcome risk of stroke