Stroke: atrial fibrillation increased the risk of stroke.

Clinical bottom line (level 1b)

  1. Male patients between the ages of 85 and 89 were at increased risk of a stroke at 3 years if they had atrial fibrillation.
  2. Female patients between the ages of 65 and 89 were at increased risk of a stroke if they had atrial fibrillation.
Wolf et al: Archives of Internal Medicine 1998; 158: 229-234
Expires November 2002

The study

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

Setting: all Medicare records, USA

26753 patients (aged range 65 to 89 years, 54% female) principal or secondary diagnoses of atrial fibrillation (International Classification of Diseases, Ninth Revision, Clinical Modification) on Medicare hospital records

Excluded if
  • atrial fibrillation on a previous admission during the preceding 2 years



    • Factors studied:
  • incidence of stroke
  • atrial fibrillation
  • atrial fibrillation
  • atrial fibrillation
  • atrial fibrillation




    • Multivariate analysis was performed to adjust for confounding factors.

    followed for 3 years
    Outcomes studied:
  • stroke
  • stroke of males aged 65 to 74
  • stroke of males aged 75 to 84
  • stroke of males aged 85 to 89
  • stroke of females aged 65 to 74
  • stroke of females aged 75 to 84
  • stroke of females aged 85 to 89

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    stroke 3 years 5173/26753 19.3%
    (18.9% to 19.8%)
    stroke of males aged 65 to 74 3 years 167/1316 12.7%
    (10.9% to 14.5%)
    stroke of males aged 75 to 84 3 years 471/2855 16.5%
    (15.1% to 17.9%)
    stroke of males aged 85 to 89 3 years 2515/8166 30.8%
    (29.8% to 31.8%)
    stroke of females aged 65 to 74 3 years 226/1859 12.2%
    (10.7% to 13.6%)
    stroke of females aged 75 to 84 3 years 1033/4796 20.9%
    (19.8% to 22.1%)
    stroke of females aged 85 to 89 3 years 1795/7761 23.1%
    (22.2% to 24.1%)

    prognostic factor for
    stroke of males aged 85 to 89     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    atrial fibrillation 3 years 1.08
    (1.02 to 1.14)     		60
    (12 to 236)

    prognostic factor for
    stroke of females aged 65 to 74     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    atrial fibrillation 3 years 1.23
    (1.02 to 1.48)     		12
    (6 to 134)

    prognostic factor for
    stroke of females aged 75 to 84     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    atrial fibrillation 3 years 1.25
    (1.14 to 1.37)     		10
    (6 to 17)

    prognostic factor for
    stroke of females aged 85 to 89     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    atrial fibrillation 3 years 1.22
    (1.15 to 1.30)     		10
    (7 to 14)

    • Males aged 65 to 74 years with atrial fibrillation cost $18,365 over 3 years, whereas those without cost $14, 474.
    • Males aged 75 to 84 years cost $14, 829, whereas those without cost $13, 915.
    • Males aged 85 to 89 years with atrial fibrillation cost $12, 029 compared with $11, 750.
    • Females aged 65 to 74 years with atrial fibrillation cost $15, 782 compared with $14, 263.
    • Females aged 75 to 84 years with atrial fibrillation cost $13, 613 compared with $11, 504.
    • Females aged 85 to 89 years with atrial fibrillation cost $11, 441 compared with $10, 992.

    Citation

    1. Wolf PA, Mitchell JB, Baker CS, et al: Impact of atrial fibrillation on mortality, stroke, and medical costs. Archives of Internal Medicine 1998; 158: 229-234
    Contributor: Clare Wotton and Bob Phillips, November 1999
    Reviewer:

    Clinical Question.
    Patient atrial fibrillation
    Intervention or Exposure does prevention or treatment
    Comparison no treatment
    Outcome alter mortality and stroke