CHADS2 score for atrial fibrillation stroke risk
Estimates stroke risk in patients with non-valvular atrial fibrillation.
Research authors: Gage BF, van Walraven C, Pearce L, Hart RG, Koudstaal PJ, Boode BS, Petersen P.
Details Formula Study characteristics Files & References
Model author
Model ID
Revision date
MeSH terms
  • Anticoagulants
  • Atrial Fibrillation
  • Clinical Prediction Rule
  • Assessment, Risk
  • Stroke
  • Model type
    Linear model (Calculation)
    No Formula defined yet
    Condition Formula

    Additional information

    The study pooled individual data from 2580 participants with nonvalvular AF who were prescribed aspirin in a multicenter trial (Atrial Fibrillation, Aspirin, Anticoagulation I study [AFASAK-1], AFASAK-2, European Atrial Fibrillation Trial, primary Prevention of Arterial Thromboembolism in patients with nonrheumatic Atrial Fibrillation in primary care study, and Stroke Prevention and Atrial Fibrillation [SPAF]-III high risk or SPAF-III low risk). There were 207 ischemic strokes during 4887 patient-years of aspirin therapy.

    Study Population

    Total population size: 2580
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    Females: {{ model.numberOfFemales }}

    Continuous characteristics

    Name Mean SD Unit
    Age 72 9 Years

    Categorical characteristics

    Name Subset / Group Nr. of patients
    Hypertension Yes 1188
    No 1392
    Prescribed aspirin Yes 2580
    No 0
    Systolic blood pressure >160 mmHg Yes 645
    No 1935
    Heart failure Yes 655
    No 1925
    Diabetes mellitus Yes 346
    No 2234
    Prior stroke or TIA Yes 566
    No 2014
    Prior myocardial infarction or angina Yes 464
    Yes 2116
    CHADS2 score for atrial fibrillation stroke risk
    Refer to Intended Use for instructions before use
    Evidencio B.V., Irenesingel 19, 7481 GJ, Haaksbergen, the Netherlands

    Total CHADS2 score:

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    Total CHADS2 score: points

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    Outcome stratification

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    Conditional information

    Result interpretation

    One recommendation suggests a 0 score is low risk and may not require anticoagulation, however there is literature that suggests that not all patients with a CHADS2 score of 0 are at low risk for ischemic stroke. Consider using the CHA2DS2-VASc score to further risk stratify patients who are identified as low risk by their CHADS2 score. For patients who are identified as moderate (score 1-2) or high risk for ischemic stroke (>3), anticoagulation therapy should be considered.

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    Calculations alone should never dictate patient care, and are no substitute for professional judgement. See our full disclaimer.

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