CHADS2 and CHA2DS2-VASc Score for Stroke Risk Assessment in Atrial Fibrillation

Atrial fibrillation (AF) is a cardiac arrhythmia with the potential to cause thromboembolism. Studies suggest that AF increases the risk of stroke five-fold.^[1] Thus, it is important to determine which patients with AF may benefit from oral anticoagulant (OAC) and possibly aspirin therapy to reduce the risk of stroke. OACs used in this setting include the following medications for stroke preventions in atiral fibrillation:

Warfarin, with a goal International Normalized Ratio (INR) of 2-3 and percent time in therapeutic INR (TTR) remains ≥ 70%
Dabigatran
Rivaroxaban
Apixaban
Edoxaban

First published in 2001, the CHADS₂ score (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke [double weight]) was developed to more accurately predict the risk of stroke in patients with nonrheumatic AF.^[2] The index was derived by combining risk factors from prior studies and then testing their validity in a cohort of 1,773 Medicare-aged patients over 2,121 patient years.^{[3, 4]} Valvular AF, which is not represented by this study, includes the presence of moderate to severe mitral stenosis or the presence of a mechanical prosthetic valve.

See Tables 1 and 2, below.

Table 1. CHADS₂ Score: Stroke Risk Assessment in Atrial Fibrillation (Open Table in a new window)

Score	CHADS₂ Risk Criteria
1 point	Congestive heart failure
1 point	Hypertension
1 point	Age ≥ 75 years
1 point	Diabetes mellitus
2 points	Stroke/transient ischemic attack

Table 2. CHADS₂ Score and Corresponding Annual Stroke Risk (Open Table in a new window)

CHADS2 Score	Adjusted Stroke Risk (%)
0	1.9
1	2.8
2	4
3	5.9
4	8.5
5	12.5
6	18.2

The above adjusted stroke rates are based on data for hospitalized patients with AF and were published in 2001.^[2] Actual stroke rates in contemporary nonhospitalized cohorts might vary from these estimates since stroke rates are decreasing^[5]

See also the Atrial Fibrillation CHADS2 Score for Stroke Risk calculator.

Although simple, the CHADS₂ score does not include many common stroke risk factors, and its limitations have been highlighted by its non-inclusion of common stroke risk factors. Even patients classified as low risk by CHADS₂ in its original validation study have a stroke rate of 1.9% per year, which is close to the criterion of a cardiovascular event rate of 20% over 10 years for primary prevention strategies (ie, statin therapy).^{[6, 7]}

Consequently, CHADS₂ was expanded to include three additional independent risk factors: vascular disease (coronary artery disease, peripheral artery disease, aortic atherosclerosis), age 65-74 years, and female sex.^{[8, 9, 10]}This more inclusive scoring system is the CHA₂DS₂-VASc score.^[11]

The CHA₂DS₂-VASc score better discriminated stroke risk in nonvalvular AF subjects with a baseline CHADS₂ score of 0 to 1; its improved predictive ability was demonstrated in a nationwide Danish registry from 1997 to 2008.^[12] In a Swedish population with nonvalvular AF,^[13]women had a moderately increased stroke risk compared with men. However, women younger than 65 years without other AF risk factors had a low risk for stroke, and it was concluded that those patients did not require OAC prophylaxis.

The 2016 European Society of Cardiology (ESC) guidelines recommend using the CHA₂DS₂-VASc score to estimate stroke risk in AF patients and to start OACs in men with a score of 1 or higher and women with a score of 2 or higher.^[14] The 2014 American Heart Association/ American College of Cardiology/ Heart Rhythm Society (AHA/ACC/HRS) guidelines also recommend the CHA₂DS₂-VASc score for the assessment of stroke risk in paitents with nonvalvular AF. Consideration of OAC prophylaxis is recommended for patients with a score of 1 and OAC use is a definite recommendation for patients with a score of 2 or greater and for those with a history of stroke or transient ischemic attack.^[15]

Use of the CHA₂DS₂-VASc score to determine stroke risk in patients having cardiac surgery independent of AF has been advocated.^[16]Stroke prevention versus bleeding risk in AF can be addressed if the HAS-BLED (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile INR, Elderly, Drugs/alcohol concomitantly) score is also calculated with the CHA₂DS₂-VASc score. See the Bleeding Risk in Atrial Fibrillation: HAS-BLED Score calculator.

See Tables 3, 4, and 5, below. See also the Atrial Fibrillation CHA2DS2-VASc Score for Stroke Risk calculator.

Table 3. CHA₂DS₂-VASc Score and Risk Criteria (Open Table in a new window)

Score	CHA₂DS₂-VASc Risk Criteria
1 point	Congestive heart failure
1 point	Hypertension
2 points	Age ≥75 years
1 point	Diabetes mellitus
2 points	Stroke/Transient Ischemic Attack/Thromboembolic event
1 point	Vascular disease (prior MI, PAD, or aortic plaque)
1 point	Age 65 to 74 years
1 point	Sex category (ie, female sex)

Table 4. CHA₂DS₂-VASc Score and Corresponding Annual Stroke Risk (Open Table in a new window)

CHA₂DS₂-VASc Score	Adjusted Stroke Risk, (% per year)
0	0
1	1.3
2	2.2
3	3.2
4	4.0
5	6.7
6	9.8
7	9.6
8	6.7
9	15.2

Adjusted stroke rate scores are based on data from Lip and colleagues.^{[5, 8, 17, 18]} The actual rates of stroke in contemporary cohorts may vary from these estimates.

Table 5. Treatment Recommendations Based on CHA₂DS₂-VASc Score^{[15, 19]} (Open Table in a new window)

CHA₂DS₂-VASc Score	Recommendation
0	None
1	None or aspirin or OAC
2 or more	OAC

Questions & Answers

Overview

Which oral anticoagulants (OAC) are used for stroke prevention in atrial fibrillation (AF)?

What is the CHADS2 score?

What is the CHA2DS2-VASc score?

Wolf PA, Abbott RD, Kannel WB. Atrial fibrillation as an independent risk factor for stroke: the Framingham Study. Stroke. 1991 Aug. 22 (8):983-8. [QxMD MEDLINE Link].
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 Jun 13. 285(22):2864-70. [QxMD MEDLINE Link].
Atrial Fibrillation investigators. Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillation. Analysis of pooled data from five randomized controlled trials. Arch Intern Med. 1994 Jul 11. 154(13):1449-57. [QxMD MEDLINE Link].
Stroke Prevention Atrial Fibrillation III Writing Committee. Patients with nonvalvular atrial fibrillation at low risk of stroke during treatment with aspirin: Stroke Prevention in Atrial Fibrillation III Study. The SPAF III Writing Committee for the Stroke Prevention in Atrial Fibrillation Investigators. JAMA. 1998 Apr 22-29. 279(16):1273-7. [QxMD MEDLINE Link].
Lip GY, Tse HF, Lane DA. Atrial fibrillation. Lancet. 2012 Feb 18. 379 (9816):648-61. [QxMD MEDLINE Link].
You JJ, Singer DE, Howard PA, Lane DA, Eckman MH, Fang MC, et al. Antithrombotic therapy for atrial fibrillation: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012 Feb. 141 (2 Suppl):e531S-75S. [QxMD MEDLINE Link].
[Guideline] Fuster V, Rydén LE, Cannom DS et al. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation. 2006 Aug 15. 114 (7):e257-354. [QxMD MEDLINE Link].
Olesen JB, Lip GY, Lane DA, Køber L, Hansen ML, Karasoy D, et al. Vascular disease and stroke risk in atrial fibrillation: a nationwide cohort study. Am J Med. 2012 Aug. 125 (8):826.e13-23. [QxMD MEDLINE Link].
Friberg L, Rosenqvist M, Lip GY. Evaluation of risk stratification schemes for ischaemic stroke and bleeding in 182 678 patients with atrial fibrillation: the Swedish Atrial Fibrillation cohort study. Eur Heart J. 2012 Jun. 33 (12):1500-10. [QxMD MEDLINE Link].
van Walraven C, Hart RG, Connolly S, Austin PC, Mant J, Hobbs FD, et al. Effect of age on stroke prevention therapy in patients with atrial fibrillation: the atrial fibrillation investigators. Stroke. 2009 Apr. 40 (4):1410-6. [QxMD MEDLINE Link].
[Guideline] Camm AJ, Lip GY, De Caterina R, Savelieva I, Atar D, Hohnloser SH, et al. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association. Eur Heart J. 2012 Nov. 33 (21):2719-47. [QxMD MEDLINE Link].
Olesen JB, Torp-Pedersen C, Hansen ML, Lip GY. The value of the CHA2DS2-VASc score for refining stroke risk stratification in patients with atrial fibrillation with a CHADS2 score 0-1: a nationwide cohort study. Thromb Haemost. 2012 Jun. 107 (6):1172-9. [QxMD MEDLINE Link].
Friberg L, Benson L, Rosenqvist M, Lip GY. Assessment of female sex as a risk factor in atrial fibrillation in Sweden: nationwide retrospective cohort study. BMJ. 2012 May 30. 344:e3522. [QxMD MEDLINE Link].
[Guideline] Kirchhof P, Benussi S, Kotecha D, Ahlsson A, Atar D, Casadei B, et al. 2016 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. Europace. 2016 Nov. 18 (11):1609-1678. [QxMD MEDLINE Link].
[Guideline] January CT, Wann LS, Alpert JS, Calkins H, Cigarroa JE, Cleveland JC Jr, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on practice guidelines and the Heart Rhythm Society. Circulation. 2014 Dec 2. 130 (23):e199-267. [QxMD MEDLINE Link]. [Full Text].
Peguero JG, Issa O, Podesta C, Elmahdy HM, Santana O, Lamas GA. Usefulness of the CHA2DS2VASc score to predict postoperative stroke in patients having cardiac surgery independent of atrial fibrillation. Am J Cardiol. 2015 Mar 15. 115 (6):758-62. [QxMD MEDLINE Link].
Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation. Chest. 2010 Feb. 137 (2):263-72. [QxMD MEDLINE Link].
Lane DA, Lip GY. Use of the CHA(2)DS(2)-VASc and HAS-BLED scores to aid decision making for thromboprophylaxis in nonvalvular atrial fibrillation. Circulation. 2012 Aug 14. 126 (7):860-5. [QxMD MEDLINE Link].
[Guideline] January CT, Wann LS, Calkins H, Chen LY, Cigarroa JE, Cleveland JC Jr, et al. 2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society in Collaboration With the Society of Thoracic Surgeons. Circulation. 2019 Jul 9. 140 (2):e125-e151. [QxMD MEDLINE Link]. [Full Text].

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Table 1. CHADS ₂ Score: Stroke Risk Assessment in Atrial Fibrillation

Score	CHADS₂ Risk Criteria
1 point	Congestive heart failure
1 point	Hypertension
1 point	Age ≥ 75 years
1 point	Diabetes mellitus
2 points	Stroke/transient ischemic attack

Table 2. CHADS ₂ Score and Corresponding Annual Stroke Risk

CHADS2 Score	Adjusted Stroke Risk (%)
0	1.9
1	2.8
2	4
3	5.9
4	8.5
5	12.5
6	18.2

Table 3. CHA ₂DS ₂-VASc Score and Risk Criteria

Score	CHA₂DS₂-VASc Risk Criteria
1 point	Congestive heart failure
1 point	Hypertension
2 points	Age ≥75 years
1 point	Diabetes mellitus
2 points	Stroke/Transient Ischemic Attack/Thromboembolic event
1 point	Vascular disease (prior MI, PAD, or aortic plaque)
1 point	Age 65 to 74 years
1 point	Sex category (ie, female sex)