By Steve S. Ryan, PhD, Updated Nov 2014
In the US, doctors use what is called a CHADS2 stroke-risk grading system to help estimate the risk of stroke in patients with atrial fibrillation. A high CHADS2 score corresponds to a greater risk of stroke, while a low CHADS2 score corresponds to a lower risk of stroke. The CHADS2 score is simple and has been validated by many studies.
The patient’s stroke risk, i.e., their CHADS2 score, is estimated by adding together the points that correspond to the patient’s conditions.
“C” Congestive Heart Failure Score = 1
“H” Hypertension Score = 1
“A” Age over 75 Score = 1
“D” Diabetes Score = 1
“S2” Previous Stroke or TIA Score = 2
A CHADS2 score of 2 or over would indicate someone should be on a blood thinner such as warfarin.
The CHADS2 score has been superseded in clinical use by the CHA2DS2-VASc score that is designed to give a better stratification of low-risk patients. It utilizes the same 5 major risk factors considered by CHADS2 but assigns a score of ‘2’ for patients older than 75 years, and adds 3 new risk factors: a history of vascular disease, age 65-74 years, and female sex which increase stroke risk. But according to the original study, “there was no statistically significant difference found between the CHA2DS2-VASc and CHADS2 risk stratification schema in predicting TE events”.
A-Fib Stroke Risk Calculators
Classification of CHADS2 vs CHA2DS-VASc
In both scoring systems, a score of 0 is “low” risk of stroke, 1 is “moderate”, and any score above 1 is a “high” risk. The CHA2DS2-VASc system has three more variables and therefore will classify a greater number of patients into a high-risk group.
Editor’s comment: There is some controversy about the increased stroke risk for females. See articles on Dr. John M’s blog post and Aging Well magazine.
See also our article: Women in A-Fib Not at Greater Risk of Stroke, and The New CHA2DS2-VASc Guidelines and the Risks of Life-Long Anticoagulation Therapy.
Last updated: Thursday, September 3, 2015