Bleeding/Clotting Risk Evaluation Tools for Atrial Fibrillation Patients

Before prescribing anticoagulants, providers should weigh the risk of thrombosis against the risk of bleeding. The tools below can be used to help providers and patients make informed decisions about whether or not anticoagulation is warranted.

Stroke Risk Scores

The CHADS2 score is a validated and widely used tool to predict stroke risk in non-valvular atrial fibrillation patients. The higher the score, the greater the stroke risk.

CHADS2 Scoring Table1
Condition Points (reset)
Congestive heart failure
Age ≥ 75 years
Diabetes mellitus
Stroke/TIA or thromboembolism (prior)
Total score =


CHADS2 Risk Stratification
Score Risk ACC/AHA Recommendation3
≥ 2 High Anticoagulate
1 Moderate Anticoagulate or ASA
Low ASA or nothing


Yearly Stroke Risk (%)
CHADS2 Score No Warfarin With Aspirin2 With Warfarin2
0 1.9 1.5 0.7
1 2.8 2.2 1.0
2 4.0 3.2 1.4
3 5.9 4.7 2.1
4 8.5 6.8 3.0
5 12.5 10.0 4.4
6 18.2 14.6 6.4


1 Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA. 2001;285(22):2864-2870 Pub Med link:

2 Robert G. Hart, MD; Lesly A. Pearce, MS; and Maria I. Aguilar, MD. Meta-analysis: Antithrombotic Therapy to Prevent Stroke in Patients Who Have Nonvalvular Atrial Fibrillation. Ann Intern Med. 2007;146:857-867

3 Anderson JL et al. Management of Patients With Atrial Fibrillation. Circulation. 2013; 127: 1916-1926