What is the CHADS2 score?

Updated: Apr 18, 2017
  • Author: Tarek Ajam, MD, MS; more...
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Answer

Answer

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 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 Medscape's 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]


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