What does CHADS₂ stand for?

CHADS₂ is an acronym for its risk factors: Congestive heart failure, Hypertension, Age 75 or over, Diabetes mellitus, and prior Stroke or TIA. Stroke or TIA scores two points (the subscript 2), and each of the other four scores one point, for a maximum of 6.

How is the CHADS₂ score interpreted?

A score of 0 is low annual stroke risk (around 1.9%), 1 is intermediate (about 2.8%), and 2 or more is high. The annual stroke rate climbs to roughly 4% at 2, 5.9% at 3, 8.5% at 4, 12.5% at 5, and 18.2% at 6 in the original validation cohort.

Should I use CHADS₂ or CHA₂DS₂-VASc?

Most current guidelines prefer CHA₂DS₂-VASc because it better identifies truly low-risk patients by adding vascular disease, age 65 to 74, and female sex. CHADS₂ remains a useful, simpler reference and is still widely cited.

Does a CHADS₂ of 0 mean no anticoagulation is needed?

A score of 0 suggests low risk, but the simpler CHADS₂ can misclassify some patients as low risk who would score higher on CHA₂DS₂-VASc. Confirm with the more granular score and weigh bleeding risk before deciding.

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CHADS₂ Stroke Risk Score

The CHADS₂ score is the original, simple tool for estimating annual stroke risk in patients with non-valvular atrial fibrillation. It is quick to apply and still widely cited, though many guidelines now prefer the more detailed CHA₂DS₂-VASc.

How it works

Each risk factor adds points; prior stroke or TIA is weighted double:

C — Congestive heart failure (or LV dysfunction): 1 point.
H — Hypertension: 1 point.
A — Age 75 years or over: 1 point.
D — Diabetes mellitus: 1 point.
S₂ — prior Stroke or TIA: 2 points.

The total ranges from 0 to 6 and maps to an estimated annual stroke rate:

0 -> 1.9%   1 -> 2.8%   2 -> 4.0%
3 -> 5.9%   4 -> 8.5%   5 -> 12.5%   6 -> 18.2%

Example and notes

A 78-year-old (1) with hypertension (1) and diabetes (1) but no heart failure or prior stroke scores 3, corresponding to roughly a 5.9% annual stroke rate — high enough that anticoagulation is generally recommended after weighing bleeding risk.

CHADS₂ tends to lump together patients the newer CHA₂DS₂-VASc would separate, so a low CHADS₂ should be confirmed against the more granular score before deciding against anticoagulation. Always balance stroke risk against bleeding risk (for example with HAS-BLED) for the individual patient.