Note: This calculator is an estimation tool based on general clinical risk weighting. For a diagnostic FRAX score used in clinical practice, please consult your healthcare provider who uses the official WHO algorithm which accounts for specific country-based epidemiological data.
function calculateFRAX() {
var age = parseFloat(document.getElementById('age').value);
var weight = parseFloat(document.getElementById('weight').value);
var height = parseFloat(document.getElementById('height').value);
var tscore = document.getElementById('tscore').value !== "" ? parseFloat(document.getElementById('tscore').value) : null;
var gender = document.getElementById('gender').value;
var prevFracture = document.getElementById('prevFracture').checked;
var parentHip = document.getElementById('parentHip').checked;
var smoker = document.getElementById('smoker').checked;
var glucocorticoids = document.getElementById('glucocorticoids').checked;
var rheumatoid = document.getElementById('rheumatoid').checked;
var secondary = document.getElementById('secondary').checked;
var alcohol = document.getElementById('alcohol').checked;
if (isNaN(age) || isNaN(weight) || isNaN(height)) {
alert("Please enter valid Age, Weight, and Height.");
return;
}
if (age 90) {
alert("FRAX is validated for ages 40 to 90.");
return;
}
// Baseline calculation based on statistical risk factor weighting
// These weights represent the approximate impact on 10-year probability
var baseMajor = 1.5;
var baseHip = 0.2;
// Age factor (Risk increases exponentially with age)
var ageFactor = Math.pow(1.06, (age – 40));
var majorRisk = baseMajor * ageFactor;
var hipRisk = baseHip * Math.pow(1.09, (age – 40));
// Sex Factor (Females generally higher risk)
if (gender === 'female') {
majorRisk *= 1.8;
hipRisk *= 1.5;
}
// Clinical Risk Factors Multipliers (Approximate relative risks)
if (prevFracture) { majorRisk *= 1.9; hipRisk *= 1.9; }
if (parentHip) { majorRisk *= 1.5; hipRisk *= 2.3; }
if (smoker) { majorRisk *= 1.4; hipRisk *= 1.6; }
if (glucocorticoids) { majorRisk *= 1.7; hipRisk *= 2.0; }
if (rheumatoid) { majorRisk *= 1.4; hipRisk *= 1.4; }
if (secondary) { majorRisk *= 1.3; hipRisk *= 1.3; }
if (alcohol) { majorRisk *= 1.4; hipRisk *= 1.4; }
// BMD (T-score) Adjustment
// For every 1 SD drop in T-score, fracture risk roughly doubles
if (tscore !== null) {
var tScoreImpact = Math.pow(2, Math.abs(tscore) / 1.0);
if (tscore < 0) {
majorRisk *= tScoreImpact;
hipRisk *= (tScoreImpact * 1.5);
} else {
majorRisk /= (1 + tscore);
hipRisk /= (1 + tscore);
}
}
// BMI Adjustment (Lower BMI increases risk)
var bmi = weight / ((height / 100) * (height / 100));
if (bmi 30) {
majorRisk *= 0.8;
hipRisk *= 0.7;
}
// Caps for realism
if (majorRisk > 99) majorRisk = 99;
if (hipRisk > 99) hipRisk = 99;
document.getElementById('majorRisk').innerText = majorRisk.toFixed(1) + "%";
document.getElementById('hipRisk').innerText = hipRisk.toFixed(1) + "%";
var recText = "";
if (hipRisk >= 3.0 || majorRisk >= 20.0) {
recText = "Risk Level: High. This score meets the NOF threshold for pharmacological treatment consideration.";
} else if (hipRisk >= 1.0 || majorRisk >= 10.0) {
recText = "Risk Level: Moderate. Discussion with a healthcare provider regarding lifestyle and preventative measures is advised.";
} else {
recText = "Risk Level: Low. Continue maintaining bone health through diet and exercise.";
}
document.getElementById('recommendation').innerText = recText;
document.getElementById('fraxResult').style.display = 'block';
}
Understanding Your FRAX® Score: The 10-Year Fracture Risk Assessment
The FRAX® (Fracture Risk Assessment Tool) is a diagnostic tool developed by the World Health Organization (WHO) to evaluate the 10-year probability of bone fractures in patients. Specifically, it calculates the risk of a major osteoporotic fracture (spine, forearm, hip, or shoulder) and the specific risk of a hip fracture.
Why the FRAX Score Matters
Bone density tests (DEXA scans) are excellent for measuring current bone strength, but they don't tell the whole story. Many people with "osteopenia" (low bone mass) experience fractures, while some with "osteoporosis" do not. The FRAX score bridges this gap by combining bone mineral density (BMD) with clinical risk factors to provide a more comprehensive view of your skeletal health.
Key Clinical Risk Factors Included in FRAX
Age: Risk increases significantly as we age, particularly over 60.
Gender: Postmenopausal women are at the highest risk due to estrogen loss.
Previous Fracture: A prior fracture as an adult (especially a "fragility fracture") is a major predictor of future events.
Parental History: A mother or father who suffered a hip fracture indicates a genetic predisposition to lower bone quality.
Glucocorticoids: Long-term use of steroid medications like Prednisone can weaken bone structure.
Lifestyle Factors: Current smoking and high alcohol consumption (3+ units per day) are detrimental to bone remodeling.
Rheumatoid Arthritis: This specific autoimmune condition is directly linked to increased bone loss.
Interpreting Your Results
In the United States, the National Osteoporosis Foundation (NOF) guidelines suggest that treatment should be considered when:
The 10-year probability of a Hip Fracture is 3% or higher.
The 10-year probability of a Major Osteoporotic Fracture is 20% or higher.
If your results fall below these thresholds, it does not mean your bones are "perfect," but rather that medication might not be the primary intervention currently recommended. Prevention through Vitamin D, calcium intake, and weight-bearing exercise remains vital for everyone.
Frequently Asked Questions
Can I calculate my FRAX score without a DEXA scan?
Yes. The FRAX tool can be calculated using Body Mass Index (BMI) if the Femoral Neck BMD (T-score) is unavailable. However, including the T-score significantly increases the accuracy of the prediction.
Is the FRAX score the same for everyone?
No. The actual WHO algorithm uses "country-specific" data. For example, a 70-year-old woman in the US may have a different risk profile than a 70-year-old woman in Japan or Italy due to differences in life expectancy and fracture epidemiology.
At what age should I get a FRAX assessment?
FRAX is designed for adults aged 40 to 90. It is most commonly used for postmenopausal women and men over the age of 50 to determine if osteoporosis treatment is necessary.
Important Medical Note: This calculator provides an estimate for educational purposes. Clinical decisions regarding medication or treatment should always be made in consultation with a physician who has access to your full medical history and official laboratory results.