Clinical tool for stroke risk stratification in Atrial Fibrillation
Score: 0
Estimated Annual Stroke Risk: 1.9%
Understanding the CHADS₂ Score
The CHADS₂ score is a clinical prediction rule used by healthcare professionals to estimate the risk of stroke in patients with non-valvular atrial fibrillation (AFib). This tool helps determine whether a patient requires anticoagulation therapy (like warfarin or NOACs) to prevent blood clots.
S₂: Stroke or Transient Ischemic Attack (TIA) history (2 points)
Stroke Risk Interpretation
CHADS₂ Score
Annual Stroke Risk (%)
Recommended Therapy
0
1.9%
Low Risk – Aspirin or No treatment
1
2.8%
Moderate Risk – Aspirin or Oral Anticoagulant
2
4.0%
High Risk – Oral Anticoagulant
3
5.9%
High Risk – Oral Anticoagulant
4
8.5%
High Risk – Oral Anticoagulant
5
12.5%
High Risk – Oral Anticoagulant
6
18.2%
High Risk – Oral Anticoagulant
CHADS₂ vs. CHA₂DS₂-VASc
While the CHADS₂ score is an excellent fundamental tool, many clinicians now prefer the CHA₂DS₂-VASc score. The "VASc" version refines risk stratification by including additional risk factors such as vascular disease, female sex, and a lower age threshold (65-74). However, CHADS₂ remains a widely recognized and simple method for initial assessment.
Example Calculation
Consider a 78-year-old patient with a history of Hypertension and Type 2 Diabetes. Their calculation would be:
Age ≥ 75: +1
Hypertension: +1
Diabetes: +1
Total Score: 3
Result: 5.9% annual risk of stroke without treatment.
Note: This calculator is for educational purposes only. Always consult with a qualified physician for medical advice and treatment decisions.
function calculateChads() {
var score = 0;
var chf = document.getElementById("chf");
var htn = document.getElementById("htn");
var age = document.getElementById("age");
var dm = document.getElementById("dm");
var stroke = document.getElementById("stroke");
var resultBox = document.getElementById("chadsResult");
var scoreDisplay = document.getElementById("scoreDisplay");
var riskDisplay = document.getElementById("riskDisplay");
if (chf.checked) score += parseInt(chf.value);
if (htn.checked) score += parseInt(htn.value);
if (age.checked) score += parseInt(age.value);
if (dm.checked) score += parseInt(dm.value);
if (stroke.checked) score += parseInt(stroke.value);
var risk = "1.9%";
var recommendation = "Low Risk";
if (score === 0) { risk = "1.9%"; recommendation = "Low Risk"; }
else if (score === 1) { risk = "2.8%"; recommendation = "Intermediate Risk"; }
else if (score === 2) { risk = "4.0%"; recommendation = "High Risk"; }
else if (score === 3) { risk = "5.9%"; recommendation = "High Risk"; }
else if (score === 4) { risk = "8.5%"; recommendation = "High Risk"; }
else if (score === 5) { risk = "12.5%"; recommendation = "High Risk"; }
else if (score === 6) { risk = "18.2%"; recommendation = "High Risk"; }
scoreDisplay.innerHTML = "Total Score: " + score;
riskDisplay.innerHTML = "Annual Stroke Risk: " + risk + "Category: " + recommendation + "";
resultBox.style.display = "block";
resultBox.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}