The CHADS 2 score is a system used to predict the risk of thromboembolic stroke in patients with atrial fibrillation helping to guide to use of anticoagulation to prevent stroke.
The CHADS 2 score has been largely replaced with the CHADS 2 vasc score. The CHADS 2 score uses age > 75, hypertension, diabetes, congestive heart failure and TIA or stroke. One point is awarded for each risk factor except TIA/stroke which gets 2 points.
The CHADS 2 score does not include an additional point (2 points) for age > 75 like the CHADS 2 Vasc score. Vascular disease history (peripheral arterial disease, previous MI, aortic atheroma) is not included in the CHADS 2 score, but is included in the CHADS 2 Vasc score.
The annual risk of stroke based on this system is below:
0 points - 1.9%
1 points - 2.8%
2 points - 4.0%
3 points - 5.9%
4 points - 8.5%
5 points - 12.5%
6 points - 18.2%
A score of 0 indicates a very low risk and aspirin alone is used from thromboembolic prophylaxis. A score of 1 in individualized in regards to using aspirin versus full anticoagulation with warfarin, dabigatran or rivaroxaban. When the CHADS 2 score is > 2, full anticoagulation is recommended unless contraindicated.