Stroke: atrial fibrillation increased the risk in over 50s.

Clinical bottom line (level 1b)

  1. Patients aged between 50 and 80 were at increased risk for stroke if they had:
    • hypertension
    • coronary heart disease
    • cardiac failure
    • atrial fibrillation
  2. Atrial fibrillation was still a risk factor in patients over 80 years old.
Wolf et al: Stroke 1991; 22: 983-988
Expires October 2003

The study

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

Setting: multicentre, USA

5070 patients (aged ?, ?% male) free from cardiovascular disease at enrolment

Factors studied:
  • stroke
  • aged 50-59 with hypertension
  • aged 60-69 with hypertension
  • aged 70-79 with hypertension
  • aged 50-59 with coronary heart disease
  • aged 60-69 with CHD
  • aged 70-79 with CHD
  • aged 50-59 with cardiac failure
  • aged 60-69 with cardiac failure
  • aged 70-79 with cardiac failure
  • aged 50-59 with atrial fibrillation
  • aged 60-69 with atrial fibrillation
  • aged 70-79 with atrial fibrillation
  • aged 80-89 with atrial fibrillation




    • Logistic regression was used to adjust for confounding factors.

    ?100% followed for 34 years
    Outcomes studied:
  • stroke

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    stroke 34 years / %
    (% to %)

    prognostic factor for
    stroke     		time to outcome adjusted RR
    (95% CI)    		 p-value
    aged 50-59 with hypertension 34 years 3.5
    ( to )     		0.001
    aged 60-69 with hypertension 34 years 3.2
    ( to )     		0.001
    aged 70-79 with hypertension 34 years 2.5
    ( to )     		0.001
    aged 50-59 with coronary heart disease 34 years 2.9
    ( to )     		0.001
    aged 60-69 with CHD 34 years 2.0
    ( to )     		0.001
    aged 70-79 with CHD 34 years 1.7
    ( to )     		0.01
    aged 50-59 with cardiac failure 34 years 3.9
    ( to )     		0.01
    aged 60-69 with cardiac failure 34 years 2.4
    ( to )     		0.001
    aged 70-79 with cardiac failure 34 years 2.2
    ( to )     		0.001
    aged 50-59 with atrial fibrillation 34 years 4.0
    ( to )     		0.001
    aged 60-69 with atrial fibrillation 34 years 2.6
    ( to )     		0.001
    aged 70-79 with atrial fibrillation 34 years 3.3
    ( to )     		0.001
    aged 80-89 with atrial fibrillation 34 years 4.5
    ( to )     		0.001

    • The cardiovascular conditions have less impact on stroke with increasing age.
    • Patients aged over 80 only have atrial fibrillation as a risk factor.

    Citation

    1. Wolf PA, Abbott RD, Kannel WB: Atrial fibrillation as an independent risk factor for stroke: The Framingham Study. Stroke 1991; 22: 983-988
    Contributor: Clare Wotton and Musab Hayatli, October 2000
    Reviewer:

    Clinical Question.
    Patient free from cardiovascular disease
    Intervention or Exposure risk factors
    Outcome stroke