Table 1

The CHADS₂ score for estimating risk of stroke in patients with AF: Points are allocated by the CHADS₂ risk criteria (congestive heart failure [symptoms in past 3 mo], 1 point; hypertension [diagnosis], 1 point; age ≥ 75 y, 1 point; diabetes mellitus, 1 point; stroke or TIA [prior], 2 points).

CHADS₂SCORE	ADJUSTED STROKE RATE, %/Y (95% CI)	*RECOMMENDED THERAPY^ (STRENGTH OF RECOMMENDATION)**
CHADS₂SCORE	ADJUSTED STROKE RATE, %/Y (95% CI)	2012 CCS GUIDELINES^{3^†}	2010 ESC⁴AND 2012 ESC TASK FORCE^‡	2012 ACCP GUIDELINES5⁵^†
0	1.9 (1.2–3.0)	No additional factors for risk of stroke: no antithrombotic treatment Female sex or vascular disease: ASA 75–325 mg/d by mouth Age ≥ 65 y or female sex and vascular disease: oral anticoagulant (grade 2C)	Calculate CHA₂DS₂-VASc score (level 1A)	No antithrombotic (grade 2B) If patient prefers therapy, ASA 75–325 mg/d (grade 2B)
1	2.8 (2.0–3.8)	Preferred: Oral anticoagulant (grade 1A) Alternative: ASA 75–325 mg/d (grade 2B)	Calculate CHA₂DS₂-VASc score (level 1A)	Preferred: Oral anticoagulant (grade 1B) Alternatives: ASA with clopidogrel (grade 2B) ASA 75–325 mg/d (grade 2B)
2	4 (3.1–5.1)	Oral anticoagulant (grade 1A)	Oral anticoagulant (level 1A)	Preferred: Oral anticoagulant (grade 1A) Alternatives: ASA with clopidogrel (grade 1B) ASA 75–325 mg/d (grade 1B)
3	5.9 (4.6–7.3)
4	8.5 (6.3–11.1)
5	12.5 (8.2–17.5)
6	18.2 (10.5–27.4)

ACCP—American College of Chest Physicians, AF—atrial fibrillation, ASA—acetylsalicylic acid, CCS—Canadian Cardiovascular Society, CHA₂DS₂-VASc—congestive heart failure; hypertension; age ≥ 75 y; diabetes mellitus; stroke or TIA (prior); vascular disease (prior myocardial infarction, peripheral artery disease, or aortic plaque); age 65–74 y; sex category (ie, female), ESC—European Society of Cardiology, TIA—transient ischemic attack.
↵* The guidelines are fairly consistent in recommendations for patients with a CHADS₂ score of ≥ 2. Varying recommendations for those with lower CHADS₂ scores reflect the need for clinical judgment in areas of uncertainty.
↵† Grade 1A is a strong recommendation based on high-quality evidence; grade 1B is a strong recommendation based on moderate-quality evidence; grade 2A is a weak or conditional recommendation based on high-quality evidence; grade 2B is a weak or conditional recommendation based on moderate-quality evidence; and grade 2C is a weak or conditional recommendation based on low- or very low-quality evidence.
↵‡ Level I evidence is evidence or general agreement that a given treatment or procedure is beneficial, useful, or effective. Level A evidence includes data derived from multiple randomized clinical trials or meta-analyses.