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CHADS Score

CHADS Score or CHADS2 Score is an clinical prediction rule for estimating the risk of stroke in patients with atrial fibrillation (AFIB), a common and usually benign heart arrythmia. It is used to determine the degree of anticoagulation therapy required,^[1] since AFIB can cause the stasis of blood in the heart chambers, leading to the formation of a mural thrombus that can dislodge into the blood flow, reaching the brain and causing a stroke. A high CHADS score corresponds to a greater risk, and vice-versa. The CHADS/CHADS2 algorithm was validated by a cohort study published in JAMA in 2001 using 1,733 Atrial fibrillation patients tracked through Medicare claims.^[2]

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1 Algorithm
2 Risk of Stroke
3 Recommendations for Anticoagulation
4 Criticism of CHADS
5 References

Algorithm

The CHADS/CHADS2 algorithm is as follows:^[3]

C:	Congestive heart failure	= 1 point
H:	Hypertension (or treated hypertension)	= 1 point
A:	Age >75 years	= 1 point
D:	Diabetes	= 1 point
S:	Prior Transient ischemic attack or Stroke	= 2 points

Risk of Stroke

According to the findings of the JAMA study, the risk of stroke as a percentage per year is:

Score	Risk of Stroke Per 100 Patient Years	95% CIs from JAMA Study
0	1.9%
1	2.8%
2	4.0%
3	5.9%
4	8.5%
5	12.5%
6	18.2%

Recommendations for Anticoagulation

The following treatment strategies were recommended by the authors of theJAMA and Circulation articles:

Score	Risk	Anticoagulation Therapy	Considerations
0	Low	Aspirin	325 mg/day most likely to offer benefit, although lower doses may be similarly efficacious
1-2	Moderate	Aspirin or Warfarin	Raise INR to 2.0-3.0, depending on factors such as patient preference
3+	High	Warfarin	Raise INR to 2.0-3.0, unless contraindicated (e.g., history of falls, clinically significant GI bleeding, inability to obtain regular INR screening)

Criticism of CHADS

The main criticism of the CHADS/CHADS2 scoring system is that someone with atrial fibrillation and a previous history of stroke, but no other risk factors (i.e. CHADS2 Score = 2), is only classified as moderate risk, whereas that person is in fact at high risk of another stroke.

References

^ Gage BF, van Walraven C, Pearce L, et al. (2004). "Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin". Circulation 110 (16): 2287–92. doi:10.1161/01.CIR.0000145172.55640.93. PMID 15477396.
^ Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ (2001). "Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation". JAMA 285 (22): 2864-70. PMID 11401607.
^ Risk of Stroke with AF. VA Palo Alto Medical Center and at Stanford University: the Sportsmedicine Program and the Cardiomyopathy Clinic. Retrieved on 2007-09-14.

Categories: Medical informatics | Medical tests

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "CHADS_Score". A list of authors is available in Wikipedia.