The FRAX Score is a widely used tool to assess an individual's 10-year probability of experiencing a major osteoporotic fracture. It takes into account various clinical risk factors and, optionally, bone mineral density (BMD) measurements. A higher FRAX score indicates a greater likelihood of fracture, prompting clinicians to consider interventions for osteoporosis prevention and management.
How FRAX Works
The FRAX algorithm was developed by the World Health Organization (WHO) and uses a combination of patient demographics and clinical risk factors. The specific formula is complex and often proprietary, involving logistic regression models tailored to different populations. Generally, the inputs are combined using weights specific to each risk factor to generate the 10-year fracture probability.
Key Input Factors:
Age: Older age is a significant risk factor for osteoporosis and fractures.
Sex: Women generally have a higher risk than men due to hormonal changes, especially after menopause.
Weight & Height: These are used to calculate Body Mass Index (BMI). Lower BMI is associated with increased fracture risk.
History of Prior Fracture: A previous fracture, particularly in the past five years, is a strong predictor of future fractures.
Parental Hip Fracture: A history of hip fracture in a parent increases an individual's risk.
Smoking: Current smokers have a higher risk of fracture.
Rheumatoid Arthritis: This autoimmune disease can negatively impact bone health.
Secondary Osteoporosis: Conditions like type 1 diabetes, malabsorption, or other endocrine disorders can weaken bones.
Alcohol Intake: Heavy alcohol consumption (defined as 3 or more units per day) is linked to increased fracture risk.
T-score: (Optional) This measures bone mineral density compared to a healthy young adult. A lower T-score (more negative) indicates lower BMD and higher fracture risk.
Interpreting the Results
The FRAX calculator provides a percentage representing the 10-year probability of a major osteoporotic fracture (which includes hip, spine, wrist, and proximal humerus fractures) and, in some versions, the 10-year probability of hip fracture specifically. These probabilities are then often interpreted in conjunction with clinical guidelines and patient-specific factors to guide treatment decisions. For example, a score above a certain threshold might trigger recommendations for pharmacological treatment, lifestyle modifications, or further diagnostic testing.
Disclaimer
This calculator is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment of osteoporosis or any health concerns.
function calculateFraxScore() {
var age = parseFloat(document.getElementById("age").value);
var sex = parseInt(document.getElementById("sex").value); // 1 for Male, 0 for Female
var weight = parseFloat(document.getElementById("weight").value);
var height_cm = parseFloat(document.getElementById("height").value);
var priorFracture = parseInt(document.getElementById("priorFracture").value);
var parentalHipFracture = parseInt(document.getElementById("parentalHipFracture").value);
var smoking = parseInt(document.getElementById("smoking").value);
var rheumatoidArthritis = parseInt(document.getElementById("rheumatoidArthritis").value);
var secondaryOsteoporosis = parseInt(document.getElementById("secondaryOsteoporosis").value);
var alcoholIntake = parseInt(document.getElementById("alcoholIntake").value);
var tnScore = parseFloat(document.getElementById("tnScore").value);
var fraxResultElement = document.getElementById("fraxResult");
var resultContainer = document.getElementById("result");
// Basic validation
if (isNaN(age) || isNaN(weight) || isNaN(height_cm) || isNaN(tnScore)) {
fraxResultElement.innerText = "Invalid Input";
resultContainer.style.borderColor = "#dc3545"; // Red border for error
return;
}
// Simplified FRAX calculation (This is a highly simplified representation.
// Actual FRAX uses complex, population-specific logistic regression models.)
// For a real-world application, you would integrate with a validated FRAX API
// or use the official software which requires licensing and is population-specific.
// The following is a conceptual demonstration and NOT medically accurate.
var baseScore = 0;
// Age component (highly simplified linear trend for demonstration)
baseScore += age * 0.05;
// Sex component (simplified for demonstration)
if (sex === 0) { // Female
baseScore += 1.5;
} else { // Male
baseScore += 0.5;
}
// BMI component (simplified)
var height_m = height_cm / 100;
var bmi = weight / (height_m * height_m);
if (bmi = 18.5 && bmi = 22 && bmi < 25) {
baseScore += 0.5;
}
// Clinical risk factors
if (priorFracture === 1) baseScore += 2.5;
if (parentalHipFracture === 1) baseScore += 1.5;
if (smoking === 1) baseScore += 1.0;
if (rheumatoidArthritis === 1) baseScore += 1.8;
if (secondaryOsteoporosis === 1) baseScore += 1.2;
if (alcoholIntake === 1) baseScore += 0.8;
// T-score component (simplified)
if (tnScore !== 0) { // Only if T-score is provided
if (tnScore = -2.5 && tnScore 30) finalFraxScore = 30;
if (finalFraxScore < 0) finalFraxScore = 0;
fraxResultElement.innerText = finalFraxScore.toFixed(2) + " %";
resultContainer.style.borderColor = "#28a745"; // Green border for success
// Add a note about the simplified calculation
var noteElement = document.createElement("span");
noteElement.innerText = "Note: This is a simplified demonstration. Consult a healthcare professional for an accurate FRAX assessment.";
noteElement.style.fontSize = "0.8rem";
noteElement.style.display = "block";
noteElement.style.marginTop = "10px";
fraxResultElement.parentNode.appendChild(noteElement);
}