4. CHADS2 and CHA2DS2 VASc

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Dr Fay reviews the simplicity of AF-stroke risk assessment with CHADS2 and CHA2DS2‑VASc.

There have been many risk scoring tools to try and determine who should be treated with an anticoagulant when it comes to AF.  However, we now see only two of these tools holding any supremacy.  One is the CHADS2 schema and the other is the, slightly more complex, CHA2DS2‑VASc schema.  These schemas are different in their fundamentals.  The CHADS2 schema is trying to identify those people at high risk of stroke, and tries to suggest who we should giving an oral anticoagulant to.  However, the way to consider the CHA2DS2‑VASc schema is that it is trying to work out at low risk of stroke.  So using the CHA2DS2‑VASc schema, we are assuming that everybody with AF should be receiving an oral anticoagulant except from those defined by the CHA2DS2‑VASc schema as being at low risk, i.e., a score of zero.

Under QOF we now see that we’re being asked to risk score our patients using the CHADS2 schema.  If this is new to a GP they will have to learn about what CHADS2 means. However, all the domains of CHADS2 are well known to the GP: congestive heart failure, hypertension, age over 75, diabetes and stroke.  Because all these conditions are within our QOF in other ways, they should be quite easy to find and, therefore, quite easily scored.  The question for the practitioner may be, should I intervene with an anticoagulant at a score of two, or should I intervene at a score of one.  A CHADS2 score of one carries an annual risk of about 4%.  I would suggest that although the QOF in our contracts is saying intervention at two; the evidence base would greatly support intervention with a CHADS2 score of one.

Please find below additional resources that you might find useful when learning about stroke prevention in AF

GRASP the initiative

A report from October 2012 on the practicalities of GRASP-AF and its benefits for primary care practitioners.  The report incudes a national summary of GRASP-AF patient treatment and a series of recommendations for commissioners and practitioners on the how stroke risk among AF patients can be reduced.
Report download

The AF Report

An expert report on AF and the prevention of stroke in the UK.  The AF Report was written for a general audience and presents a thorough and current distillation of the evidence and issues in AF stroke prevention.  The report also identifies current challenges and areas where action is needed to improve the care of AF patients. Download report

The AF Stroke Risk Calculator

A simple online tool for the calculation of CHADS2 and CHADSVASc scores for AF patients.  The calculator was designed to be intuitive and sufficiently easy-to-use for patients to calculate their own risk of stroke.


The NHS Improving Quality website contains a wealth of helpful, practical information on GRASP-AF

The videos

Below are video clips from Dr Matt Fat and Dr Andreas Wolff on several aspects of AF patient care and the reduction of stroke risk.