CHADS₂ Score
Original stroke risk score for atrial fibrillation (predecessor to CHA₂DS₂-VASc)
Calculator
Why use it
Simple, rapid stroke risk estimation in AF. Still referenced in some guidelines. Useful when quick bedside assessment is needed.
About
CHADS₂ is the original clinical prediction rule for estimating stroke risk in patients with non-valvular atrial fibrillation. It has been largely superseded by CHA₂DS₂-VASc which provides better risk stratification in low-risk patients, but CHADS₂ remains historically important and is still referenced in some guidelines and clinical settings.
When to use
- Atrial fibrillation — stroke risk stratification
- Quick assessment when CHA₂DS₂-VASc is not needed for decision-making
Formula
Pearls & pitfalls
- CHA₂DS₂-VASc has replaced CHADS₂ in most current guidelines (ESC, AHA/ACC).
- CHADS₂ groups many patients as "intermediate risk" (score 1) where CHA₂DS₂-VASc provides clearer guidance.
- Prior stroke/TIA carries the highest weight (+2 points) reflecting its strong predictive value.
- CHADS₂ = 0 does NOT mean zero risk — annual stroke rate is still ~1.9%.
Next steps
CHADS₂ 0: Low risk — aspirin or no therapy. CHADS₂ 1: Intermediate — anticoagulation or aspirin. CHADS₂ ≥ 2: High risk — anticoagulation recommended. Note: CHA₂DS₂-VASc is preferred by current guidelines.
Evidence
Derived by Gage et al. (JAMA, 2001) from the National Registry of AF and AF Investigators pooled dataset. Validated in multiple cohorts. C-statistic ~0.82 for stroke prediction.
References
- Gage BF et al. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA. 2001;285(22):2864-2870. — link