CHADS₂ Score Calculator
Stroke Risk Stratification for Atrial Fibrillation
Select all clinical criteria that apply to the patient:
Patient Score
0
Low Risk
Annual Stroke Risk: 1.9%
What is the CHADS₂ Score?
The CHADS₂ score is a validated clinical prediction rule used by healthcare professionals to estimate the risk of stroke in patients with non-valvular atrial fibrillation (AFib). AFib is a heart rhythm disorder that significantly increases the likelihood of blood clots forming in the heart, which can then travel to the brain and cause an ischemic stroke.
Scoring Breakdown
- C (Congestive Heart Failure): Recent heart failure exacerbation or history of heart failure (1 point).
- H (Hypertension): Blood pressure consistently >140/90 mmHg or treated hypertension (1 point).
- A (Age): Patient is 75 years of age or older (1 point).
- D (Diabetes): History of diabetes mellitus (1 point).
- S₂ (Stroke/TIA): Previous history of stroke, transient ischemic attack (TIA), or thromboembolism (2 points).
Interpretation and Annual Risk
| CHADS₂ Score |
Adjusted Stroke Rate (%/yr) |
Risk Category |
| 0 | 1.9% | Low |
| 1 | 2.8% | Low-Intermediate |
| 2 | 4.0% | Intermediate |
| 3 | 5.9% | High |
| 4 | 8.5% | High |
| 5 | 12.5% | High |
| 6 | 18.2% | High |
Example Calculation
Consider a 78-year-old patient (1 point) with a history of Hypertension (1 point) but no history of heart failure, diabetes, or previous stroke. Their total CHADS₂ score would be 2. This places them in the intermediate risk category with a projected annual stroke risk of approximately 4.0% without anticoagulation therapy.
Medical Disclaimer: This tool is for educational purposes only. Treatment decisions regarding anticoagulation (like warfarin or NOACs) should always be made by a qualified healthcare professional based on a comprehensive clinical assessment. Many clinicians now use the updated CHA₂DS₂-VASc score for more detailed risk assessment.
function calculateCHADSScore() {
var score = 0;
// Get checkbox values
var c = document.getElementById("congestive").checked;
var h = document.getElementById("hypertension").checked;
var a = document.getElementById("age").checked;
var d = document.getElementById("diabetes").checked;
var s = document.getElementById("stroke").checked;
// Sum points
if (c) score += 1;
if (h) score += 1;
if (a) score += 1;
if (d) score += 1;
if (s) score += 2;
// Risk Mapping
var riskText = "";
var strokeRate = "";
var bgColor = "";
var textColor = "#fff";
switch(score) {
case 0:
riskText = "Low Risk";
strokeRate = "1.9%";
bgColor = "#27ae60";
break;
case 1:
riskText = "Low-Intermediate Risk";
strokeRate = "2.8%";
bgColor = "#f1c40f";
textColor = "#333";
break;
case 2:
riskText = "Intermediate Risk";
strokeRate = "4.0%";
bgColor = "#e67e22";
break;
case 3:
riskText = "High Risk";
strokeRate = "5.9%";
bgColor = "#e74c3c";
break;
case 4:
riskText = "High Risk";
strokeRate = "8.5%";
bgColor = "#c0392b";
break;
case 5:
riskText = "High Risk";
strokeRate = "12.5%";
bgColor = "#96281b";
break;
case 6:
riskText = "High Risk";
strokeRate = "18.2%";
bgColor = "#6c1a11";
break;
default:
riskText = "Invalid Calculation";
strokeRate = "-";
bgColor = "#7f8c8d";
}
// Update UI
document.getElementById("score-display").innerText = score;
document.getElementById("risk-level").innerText = riskText;
document.getElementById("risk-level").style.backgroundColor = bgColor;
document.getElementById("risk-level").style.color = textColor;
document.getElementById("stroke-rate").innerText = "Estimated Annual Stroke Risk: " + strokeRate;
// Show Result Area
document.getElementById("chads-result-area").style.display = "block";
document.getElementById("chads-result-area").style.borderColor = bgColor;
// Scroll to result
document.getElementById("chads-result-area").scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}