Stroke: current smoking increased the risk for nonfatal and ischaemic strokes.

Clinical bottom line (level 1b)

  1. Middle-aged men were at increased risk of stroke over ~10y follow-up if they were smokers. (NNF = 82 for 9.7 years)
  2. The risk was higher if they reported smoking more cigarettes (>20/day) (NNF = 41 for 9.7 years)
Robbins et al: Annals of Internal Medicine 1994; 120: 458-462
Expires November 2002

The study

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

Setting: participants of the Physicians' Health Study

22071 patients (aged range 40 to 84 years, 100% male) physicians: free from self-reported myocardial infarction, stroke and transient ischaemic attack

Factors studied:
  • current smokers 1 to 19 cigarettes/day
  • current smokers, = or > 20 cigarettes/day
  • current smoker, 1-19 cigarettes/day
  • = or >20 cigarettes/day




    • Multivariate analyses were performed to adjust for confounding factors.

    100% followed for mean 9.7 years
    Outcomes studied:
  • nonfatal stroke
  • fatal stroke
  • ischaemic stroke
  • haemorrhagic stroke

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    nonfatal stroke mean 9.7 years 312/22071 1.41%
    (1.26% to 1.57%)
    fatal stroke mean 9.7 years 28/22071 0.13%
    (0.08% to 0.17%)
    ischaemic stroke mean 9.7 years 275/22071 1.25%
    (1.10% to 1.39%)
    haemorrhagic stroke mean 9.7 years 56/22071 0.25%
    (0.19% to 0.32%)

    prognostic factor for
    nonfatal stroke     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    current smokers 1 to 19 cigarettes/day mean 9.7 years 1.86
    (1.04 to 3.33)     		82
    (30 to 1773)
    current smokers, = or > 20 cigarettes/day mean 9.7 years 2.71
    (1.84 to 3.98)     		41
    (24 to 84)

    prognostic factor for
    ischaemic stroke     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    current smoker, 1-19 cigarettes/day mean 9.7 years 2.02
    (1.10 to 3.70)     		78
    (30 to 800)
    = or >20 cigarettes/day mean 9.7 years 2.70
    (1.77 to 4.10)     		47
    (26 to 104)

    • Smoking assessed by self-report from mailed questionnaire
    • Smokers or former smokers compared with never smokers (control).
    • Former smokers had no significant increased risk of stroke.
    • There was no significant difference in the categories of alcohol drinking across the smoking categories. A full analysis was restricted by lack of data.

    Comments

    1. Data was taken from a randomised trial of aspirin and beta-carotene.

    Citation

    1. Robbins AS, Manson JE, Lee I-M, et al: Cigarette smoking and stroke in a cohort of U.S. male physicians. Annals of Internal Medicine 1994; 120: 458-462
    Contributor: Clare Wotton and Bob Phillips, November 1999
    Reviewer:

    Clinical Question.
    Patient male physicians
    Intervention or Exposure cigarette smoking
    Comparison no smoking
    Outcome stroke