Cardiology
CHADS₂ Score
Older stroke-risk score in atrial fibrillation.
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
CHADS₂ is an older score that estimates stroke risk in people with non-valvular atrial fibrillation (AF). It awards one point each for Congestive heart failure, Hypertension, Age ≥75 and Diabetes, and two points for a prior Stroke or transient ischaemic attack, giving a maximum of 6. It was widely used to guide anticoagulation decisions before being largely superseded by CHA₂DS₂-VASc. The newer score adds further risk factors and is better at identifying truly low-risk patients.
Interpreting the result
A score of 0 is regarded as low risk, 1–2 as moderate and 3 or more as high risk, with annual stroke risk rising as the score increases. Historically, anticoagulation was often considered from a score of 1 or 2 upwards. Because CHADS₂ classifies some genuinely higher-risk patients as low, current guidance prefers CHA₂DS₂-VASc, which more reliably identifies people who can safely avoid anticoagulation.
Advice
Consider CHA₂DS₂-VASc for a more sensitive assessment of low-risk patients.
Worked example
A patient with hypertension (1) and diabetes (1) scores CHADS₂ 2, a moderate-risk category. In contemporary practice this patient would also be assessed with CHA₂DS₂-VASc to refine the decision about anticoagulation.
Pearls / pitfalls
- CHADS₂ is largely superseded by CHA₂DS₂-VASc, which better identifies truly low-risk patients — prefer the newer score where possible.
- A CHADS₂ of 0 is not as reassuring as it seems, because the score omits vascular disease, the 65–74 age band and sex.
- Like other stroke scores, it estimates stroke risk only and should be paired with a separate bleeding-risk assessment.
- It does not apply to valvular AF (mechanical valves or moderate-to-severe mitral stenosis), which requires anticoagulation regardless.
Evidence & validation
CHADS₂ was validated by Gage et al. in 2001 and was the standard AF stroke-risk tool for over a decade, before CHA₂DS₂-VASc was adopted by ESC and NICE as the preferred score.
Frequently asked questions
Should I still use CHADS₂?
CHA₂DS₂-VASc is now preferred in UK and international guidance because it better identifies truly low-risk patients. CHADS₂ is mainly useful where it is specifically referenced or for historical comparison.
What is the difference from CHA₂DS₂-VASc?
CHA₂DS₂-VASc adds vascular disease, the 65–74 age band and female sex category. This makes it more sensitive at identifying low-risk people who can avoid anticoagulation.
What CHADS₂ score is high risk?
A score of 0 is low, 1–2 moderate and 3 or more high risk. Annual stroke risk rises as the score increases.
Does CHADS₂ assess bleeding risk?
No. It estimates stroke risk only. Bleeding risk should be assessed separately, for example with HAS-BLED.
Can CHADS₂ be used in valvular AF?
No. Patients with mechanical valves or moderate-to-severe mitral stenosis need anticoagulation regardless of any stroke-risk score.
References
- Gage BF, Waterman AD, Shannon W, et al. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA. 2001;285(22):2864–2870.
- NICE NG196: Atrial fibrillation: diagnosis and management. 2021.
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