CHA2DS2–VASc score
CHADS score or CHADS2 score is a clinical prediction rule for estimating the risk of stroke in patients with atrial fibrillation (AF), a common and usually benign heart arrythmia. It is used to determine the degree of anticoagulation therapy required,[1] since AF can cause 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 of stroke, and vice-versa. The CHADS/CHADS2 score was validated by a cohort study published in JAMA in 2001 using 1,733 atrial fibrillation patients tracked through Medicare claims who were not prescribed the anticoagulant warfarin.[2]
Method
The CHADS/CHADS2 scoring table is shown below:[3]
| Condition | Points | |
|---|---|---|
| C | Congestive heart failure | |
| H | Hypertension (or treated hypertension) | |
| A | Age >75 years | |
| D | Diabetes | |
| S2 | Prior Transient ischemic attack or Stroke |
Adding together the points that correspond to the conditions that a patient has will result in the CHADS2 score. This score is used in the next section to estimate stroke risk.
Risk of stroke
According to the findings of the JAMA study, the risk of stroke as a percentage per year is:
| CHADS2 Score | Stroke Risk % | 95% CI |
|---|---|---|
To understand what this table means, let's consider a special type of casino that has a game of chance called Wheel of Misfortune. For example, suppose you have a CHADS2 score of 2 and you don't take the anticoagulant warfarin. Then your annual risk of stroke is 4%. The corresponding Wheel of Misfortune would have 100 possible places to end up on with 4 of the places marked with the word "stroke" and 96 of the places marked with "safe". Being a strange casino, a bet is placed for you once a year on any day without your knowledge. When your Wheel of Misfortune is spun, ending up on any one of the 4 "stroke" places would cause you to have a stroke and ending up on any of the other 96 places would be safe. This is similar to what a 4% annual stroke risk means.
However, warfarin has its own stroke risk and drawbacks which were considered in developing the recommendations of the next section.
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 | Moderate | Aspirin or Warfarin | ASA daily or Raise INR to 2.0-3.0, depending on factors such as patient preference |
| 2 or greater | Moderate or 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) |
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.
{{cite journal}}: Explicit use of et al. in:|author=(help)CS1 maint: multiple names: authors list (link) - ^ 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.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "Risk of Stroke with AF". VA Palo Alto Medical Center and at Stanford University: the Sportsmedicine Program and the Cardiomyopathy Clinic. Retrieved 2007-09-14.