CHA2DS2–VASc score

The CHADS2 score and its updated version, the CHA2DS2-VASc score, are clinical prediction rules for estimating the risk of stroke in patients with non-rheumatic atrial fibrillation (AF), a common and serious heart arrhythmia associated with thromboembolic stroke. Such a score is used to determine whether or not treatment is required with anticoagulation therapy or antiplatelet therapy, since AF can cause stasis of blood in the upper heart chambers, leading to the formation of a mural thrombus that can dislodge into the blood flow, reach the brain, cut off supply to the brain, and cause a stroke. The CHADS2 score and its updated version, the CHA2DS2-VASc score, are clinical prediction rules for estimating the risk of stroke in patients with non-rheumatic atrial fibrillation (AF), a common and serious heart arrhythmia associated with thromboembolic stroke. Such a score is used to determine whether or not treatment is required with anticoagulation therapy or antiplatelet therapy, since AF can cause stasis of blood in the upper heart chambers, leading to the formation of a mural thrombus that can dislodge into the blood flow, reach the brain, cut off supply to the brain, and cause a stroke. A high score corresponds to a greater risk of stroke, while a low score corresponds to a lower risk of stroke. The CHADS2 score is simple and has been validated by many studies. In clinical use, the CHADS2 score (pronounced 'chads two') has been superseded by the CHA2DS2-VASc score ('chads vasc'), which gives a better stratification of low-risk patients. The CHADS2 score does not include some common stroke risk factors, and its various pros/cons have been carefully discussed. Adding together the points that correspond to the conditions that are present results in the CHADS2 score, that is used to estimate stroke risk. To complement the CHADS2 score, by the inclusion of additional 'stroke risk modifier' risk factors, the CHA2DS2-VASc-score has been proposed. In clinical use, the CHADS2 score has been superseded by the CHA2DS2-VASc score, which gives a better stratification of low-risk patients. The CHADS2 score has been outperformed by the CHA2DS2-VASc in multiple patient groups including patients with AF who are receiving outpatient elective electrical cardioversion. Thus, the CHA2DS2-VASc score is a refinement of CHADS2 score and extends the latter by including additional common stroke risk factors, that is, age 65–74, female gender and vascular disease. In the CHA2DS2-VASc score, 'age 75 and above' also has extra weight, with 2 points. The maximum CHADS2 score is 6, whilst the maximum CHA2DS2-VASc score is 9 (not 10, as might be expected from simply adding up the columns; the maximum score for age is 2 points). Major guidelines have used the above fixed annual stroke risk as a guideline of starting anticoagulant treatment; where the ischemic stroke risk of more than 1% to 2% should be an indication to start an anticoagulant therapy. However, actual risk of getting stroke varies according to sampling method and geographical regions, as well as use of appropriate study analysis methodology. A meta-analysis of various studies in 2015 shown that annual stroke risk is less than 1% in 13 of the 17 studies for CHA2DS2–VASc score of 1, 6 out of 15 studies reported risk of 1 to 2% and 5 out of 15 studies reported risk of more than 2% for CHA2DS2–VASc score of 2. Nevertheless, stroke rates vary by study setting (hospital vs community), population (trial vs general), ethnicity, etc. Some studies included in the metaanalysis include females with score 1 by virtue of gender (who are low risk), into the aggregate rates; others included do not account for followup anticoagulation use (thus lowering rates) and were analysed by excluding all patients ever started on anticoagulants ('conditioning on the future' error). The CHA2DS2-VASc Score has shown increasing popularity over time while the CHADS2 has shown decreasing popularity, which could 'partly be related to introduction of guidelines recommending the use of the CHA2DS2-VASc score for stroke risk stratification'.