Legacy CHADS₂ Model • See CHA₂DS₂-VASc for current guidelines
Risk Triage Ready
Select clinical history to see statistical annual risk.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
Clinical Use
Initial stroke risk stratification for patients with non-valvular atrial fibrillation.
Identifying high-risk patients who require oral anticoagulation.
Historical comparison for longitudinal patient tracking.
Guideline Note
While CHADS₂ was the gold standard for over a decade, the 2020 ESC and 2023 ACC/AHA guidelines now prefer the CHA₂DS₂-VASc score for its better sensitivity in identifying "truly low-risk" patients.
Section 2
Formula & Logic
Scoring variables
C: Congestive Heart Failure
1 pt
H: Hypertension
1 pt
A: Age ≥ 75
1 pt
D: Diabetes Mellitus
1 pt
S₂: Prior Stroke or TIA
2 pts
Interpretation of Risk
Score 0
1.9% annual risk (Low)
Score 1
2.8% annual risk (Intermediate)
Score 2+
4.0% - 18.2% annual risk (High)
Section 3
Pearls/Pitfalls
The CHADS₂ "Gray Zone"
The major limitation of CHADS₂ is that many patients categorized as "low risk" (score of 0 or 1) still have a stroke rate of nearly 2% per year. This led to the development of the more sensitive CHA₂DS₂-VASc model.
Key Pearl
Prior Stroke or TIA is the single strongest predictor of a recurrent event, which is why it receives a double weight (2 points) in this and subsequent models.
Section 4
Next Steps
Management Recommendations
01
Score 0: Low risk. Aspirin used to be recommended, but now "no treatment" is often preferred if the CHA₂DS₂-VASc is also 0.
02
Score 1: Intermediate risk. Consider oral anticoagulation (DOAC preferred) or aspirin based on patient preference.
03
Score ≥ 2: High risk. Oral anticoagulation is strongly recommended unless absolute contraindications exist.
Section 5
Evidence Appraisal
Primary Derivation
Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation.
Gage BF et al. • JAMA.. 2001;n=1,733. Combined the AFI and SPAF models into the modern CHADS₂ score.
Section 6
Literature
Combining the Evidence
Before 2001, doctors used multiple competing models (AFI and SPAF) to guess stroke risk. Dr. Brian Gage and his team performed a meta-analysis to create a single, easy-to-remember mnemonic. CHADS₂ dominated cardiology for 15 years before being refined into the VASc model we use today.
