CHADS2 Score Calculator

Calculate the CHADS2 Score to assess ischemic stroke risk in patients with non-rheumatic atrial fibrillation. Check off each clinical risk factor — Congestive Heart Failure, Hypertension, Age ≥75, Diabetes Mellitus, and prior Stroke/TIA — and your CHADS2 Score and corresponding annual stroke risk percentage are calculated with antithrombotic therapy guidance.

Disclaimer: This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any health-related decisions.

Congestive Heart Failure (or LV dysfunction) *

History of CHF or left ventricular systolic dysfunction

Hypertension *

Resting blood pressure >140/90 mmHg on at least 2 occasions, or current antihypertensive treatment

Age ≥75 Years *

Patient is 75 years of age or older

Diabetes Mellitus *

Fasting glucose >125 mg/dL or treatment with oral hypoglycemic agent or insulin

Prior Stroke or TIA *

Previous stroke, TIA, or thromboembolism — counts as 2 points (the 'S2' in CHADS2)

Results

CHADS2 Score

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Estimated Annual Stroke Risk

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Risk Category

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Antithrombotic Therapy Guidance

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Results Table

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Frequently Asked Questions

What does CHADS2 stand for?

CHADS2 is an acronym for the five clinical risk factors it evaluates: Congestive heart failure (1 pt), Hypertension (1 pt), Age ≥75 years (1 pt), Diabetes mellitus (1 pt), and prior Stroke or TIA (2 pts). The 'S2' gets double weight because prior stroke is the strongest predictor of future stroke in AF patients.

What is a high vs. low CHADS2 score?

A score of 0 indicates low risk (~1.9% annual stroke risk), a score of 1–2 indicates moderate risk, and a score of 3 or higher indicates high risk (up to ~18.2% annually at a score of 6). Patients with higher scores generally benefit the most from oral anticoagulation therapy.

What antithrombotic therapy is recommended based on the CHADS2 score?

A score of 0 typically warrants aspirin or no therapy. A score of 1 may use aspirin or oral anticoagulation depending on clinical judgment. Scores of 2 or higher generally warrant oral anticoagulation (e.g., warfarin or a DOAC) unless contraindicated. Always consult current clinical guidelines and individualize patient care.

How does CHADS2 differ from CHA2DS2-VASc?

CHA2DS2-VASc is the more modern and comprehensive score that adds vascular disease, age 65–74, and female sex as additional risk factors. It was developed to better stratify low-risk patients and is now preferred in most current guidelines. CHADS2 remains useful as a quick bedside tool and for historical reference.

Is CHADS2 validated for all types of atrial fibrillation?

The CHADS2 score was specifically developed and validated for non-rheumatic atrial fibrillation. Patients with rheumatic AF (e.g., mitral stenosis) are already considered high risk and typically require anticoagulation regardless of CHADS2 score.

Can CHADS2 be used to assess bleeding risk?

No — CHADS2 evaluates stroke risk only, not bleeding risk. To assess bleeding risk associated with anticoagulation, separate tools such as the HAS-BLED score should be used alongside CHADS2 when making treatment decisions.

Who developed the CHADS2 score?

The CHADS2 score was developed by Gage et al. and published in JAMA in 2001. It was derived from a combination of the AFI (Atrial Fibrillation Investigators) and SPAF (Stroke Prevention in Atrial Fibrillation) stroke risk criteria and validated in a large Medicare database of AF patients.

What are the limitations of the CHADS2 score?

CHADS2 has been criticized for suboptimal discrimination, particularly in identifying truly low-risk patients who might not need anticoagulation. It does not account for several additional risk factors such as vascular disease or sex. For these reasons, CHA2DS2-VASc is now recommended by major guidelines (ESC, ACC/AHA) over CHADS2.