Chads 2 Calculator

CHADS₂ Score Calculator

function calculateCHADS2() { var score = 0; if (document.getElementById('chfInput').checked) { score += 1; } if (document.getElementById('hypertensionInput').checked) { score += 1; } if (document.getElementById('age75Input').checked) { score += 1; } if (document.getElementById('diabetesInput').checked) { score += 1; } if (document.getElementById('strokeTIAInput').checked) { score += 2; } var resultDiv = document.getElementById('chads2Result'); var interpretation = "; var strokeRisk = "; switch (score) { case 0: interpretation = 'Low risk of stroke.'; strokeRisk = 'Approximately 1.9% per year.'; break; case 1: interpretation = 'Low-moderate risk of stroke.'; strokeRisk = 'Approximately 2.8% per year.'; break; case 2: interpretation = 'Moderate risk of stroke.'; strokeRisk = 'Approximately 4.0% per year.'; break; case 3: interpretation = 'Moderate-high risk of stroke.'; strokeRisk = 'Approximately 5.9% per year.'; break; case 4: interpretation = 'High risk of stroke.'; strokeRisk = 'Approximately 8.5% per year.'; break; case 5: interpretation = 'High risk of stroke.'; strokeRisk = 'Approximately 12.5% per year.'; break; case 6: interpretation = 'Very high risk of stroke.'; strokeRisk = 'Approximately 18.2% per year.'; break; default: interpretation = 'Invalid score.'; strokeRisk = "; } resultDiv.innerHTML = '

Your CHADS₂ Score: ' + score + '

' + 'Interpretation: ' + interpretation + " + 'Estimated Annual Stroke Risk: ' + strokeRisk + " + 'This calculator is for informational purposes only and should not replace professional medical advice.'; resultDiv.style.display = 'block'; }

Understanding the CHADS₂ Score for Atrial Fibrillation

The CHADS₂ score is a clinical prediction rule used to estimate the risk of stroke in patients with non-valvular atrial fibrillation (AFib). Atrial fibrillation is an irregular and often rapid heart rate that can lead to blood clots forming in the heart. If these clots travel to the brain, they can cause a stroke. The CHADS₂ score helps healthcare providers determine which patients might benefit from anticoagulant therapy (blood thinners) to reduce this risk.

Components of the CHADS₂ Score

The acronym CHADS₂ stands for the following risk factors, each contributing a specific number of points to the total score:

• C – Congestive Heart Failure (1 point): A history of heart failure significantly increases stroke risk.
• H – Hypertension (High Blood Pressure) (1 point): Uncontrolled high blood pressure is a major risk factor for stroke.
• A – Age ≥ 75 years (1 point): Older age is a strong independent risk factor for stroke.
• D – Diabetes Mellitus (1 point): Diabetes can damage blood vessels, increasing stroke risk.
• S₂ – Prior Stroke, Transient Ischemic Attack (TIA), or Thromboembolism (2 points): A previous stroke or TIA is the strongest predictor of future stroke, hence it carries double the points.

How to Use the CHADS₂ Calculator

Using the calculator above is straightforward:

1. Identify Risk Factors: Review the patient's medical history for each of the CHADS₂ criteria.
2. Check Boxes: Select the checkboxes corresponding to the risk factors that are present.
3. Calculate Score: Click the "Calculate CHADS₂ Score" button.
4. Interpret Result: The calculator will display the total score and an estimated annual stroke risk percentage.

Interpreting Your CHADS₂ Score

The total CHADS₂ score ranges from 0 to 6. A higher score indicates a greater risk of stroke. Here's a general interpretation:

• Score 0: Low risk.
• Score 1: Low-moderate risk.
• Score 2: Moderate risk.
• Score ≥ 3: Moderate to high risk.

For example, a patient with a CHADS₂ score of 0 has an annual stroke risk of about 1.9%, while a patient with a score of 6 has an annual stroke risk of about 18.2% without antithrombotic therapy.

Clinical Significance and Limitations

The CHADS₂ score is a valuable tool for initial risk stratification. Patients with a score of 0 or 1 might be considered for aspirin or no antithrombotic therapy, while those with a score of 2 or more are generally recommended for oral anticoagulation (e.g., warfarin or direct oral anticoagulants) to significantly reduce their stroke risk.

It's important to note that the CHADS₂ score has been largely superseded by the more comprehensive CHA₂DS₂-VASc score, which includes additional risk factors like vascular disease, age 65-74 years, and female sex, providing a more nuanced risk assessment, especially for patients with lower CHADS₂ scores. However, CHADS₂ remains a foundational concept in AFib management.

Disclaimer: This CHADS₂ calculator is intended for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider for any health concerns or before making any decisions related to your health or treatment.