Frax Calculator

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FRAX® Fracture Risk Assessment
Female Male
No Yes
No Yes
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Your Assessment Results
Major Osteoporotic Fracture Risk: 0.0%
Hip Fracture Risk: 0.0%

What is the FRAX Calculator?

The Fracture Risk Assessment Tool (FRAX) is a diagnostic tool developed by the World Health Organization (WHO) to evaluate the 10-year probability of bone fractures in patients. It specifically calculates the risk of a major osteoporotic fracture (spine, forearm, hip, or shoulder) and the specific risk of a hip fracture.

How Risk Factors Influence Your Score

This calculator evaluates several key clinical risk factors that impact bone density and structural integrity:

  • Age: Risk increases significantly as you age, particularly after 65.
  • Body Mass Index (BMI): Lower body weight (low BMI) is a significant risk factor for bone loss.
  • Glucocorticoids: Long-term use of steroid medications like Prednisone can weaken bone tissue.
  • Previous Fractures: A history of "fragility fractures" (broken bones from a minor fall) is the strongest predictor of future events.
  • Secondary Osteoporosis: Conditions like Type 1 Diabetes or untreated hyperthyroidism increase risk.

Understanding Your Results

Typically, a 10-year risk of a major osteoporotic fracture greater than 20% or a hip fracture risk greater than 3% is considered a threshold where clinicians may recommend pharmacological intervention (bone-building or bone-preserving medications).

Practical Examples

Example A: A 70-year-old female weighing 55kg (low BMI) with a parent who suffered a hip fracture. Even without a personal history of fractures, her risk may exceed 15% due to genetics and weight.

Example B: A 50-year-old male who smokes and uses glucocorticoids for asthma. His risk might be relatively low now (e.g., 4%), but his "preventative" score highlights factors he can change to avoid high risk later in life.

function calculateFRAX() { var age = parseFloat(document.getElementById('frax-age').value); var weight = parseFloat(document.getElementById('frax-weight').value); var height = parseFloat(document.getElementById('frax-height').value); var gender = document.getElementById('frax-gender').value; var prevFrac = parseInt(document.getElementById('frax-prev-frac').value); var parentHip = parseInt(document.getElementById('frax-parent-hip').value); var smoking = parseInt(document.getElementById('frax-smoking').value); var steroids = parseInt(document.getElementById('frax-steroids').value); var arthritis = parseInt(document.getElementById('frax-arthritis').value); var alcohol = parseInt(document.getElementById('frax-alcohol').value); if (isNaN(age) || isNaN(weight) || isNaN(height)) { alert("Please enter valid numbers for age, weight, and height."); return; } if (age 90) { alert("The FRAX algorithm is validated for ages 40 to 90."); } // Calculate BMI var heightM = height / 100; var bmi = weight / (heightM * heightM); // BASE RISK MODEL (Approximated based on WHO general risk curves) // Starting base at age 40 for a healthy individual var baseMajor = 1.5; var baseHip = 0.2; // Age Factor: Risk roughly doubles every 10 years after 50 var ageFactor = Math.pow(1.07, (age – 40)); // Gender Factor: Females generally have 2x the risk of males for major fractures var genderMultiplier = (gender === 'female') ? 2.0 : 1.0; // BMI Factor: Lower BMI increases risk var bmiMultiplier = 1.0; if (bmi 25 && bmi = 30) bmiMultiplier = 0.7; var riskMajor = baseMajor * ageFactor * genderMultiplier * bmiMultiplier; var riskHip = baseHip * Math.pow(1.09, (age – 40)) * (gender === 'female' ? 1.8 : 1.0) * bmiMultiplier; // Additive Clinical Risk Factors (Multipliers) if (prevFrac === 1) { riskMajor *= 1.9; riskHip *= 1.9; } if (parentHip === 1) { riskMajor *= 1.6; riskHip *= 2.3; } if (smoking === 1) { riskMajor *= 1.2; riskHip *= 1.3; } if (steroids === 1) { riskMajor *= 1.7; riskHip *= 1.9; } if (arthritis === 1) { riskMajor *= 1.3; riskHip *= 1.2; } if (alcohol === 1) { riskMajor *= 1.2; riskHip *= 1.4; } // Cap risks at logical levels if (riskMajor > 95) riskMajor = 95; if (riskHip > 95) riskHip = 95; // Update UI document.getElementById('res-major').innerText = riskMajor.toFixed(1) + "%"; document.getElementById('res-hip').innerText = riskHip.toFixed(1) + "%"; var interpretation = ""; if (riskMajor >= 20 || riskHip >= 3) { interpretation = "Result indicates high 10-year fracture risk. Consult a healthcare professional about bone density testing (DEXA scan)."; document.getElementById('frax-results').style.borderColor = "#e74c3c"; } else { interpretation = "Result indicates low to moderate 10-year fracture risk. Maintain adequate Calcium and Vitamin D intake."; document.getElementById('frax-results').style.borderColor = "#27ae60"; } document.getElementById('risk-interpretation').innerText = interpretation; document.getElementById('frax-results').style.display = "block"; // Scroll to results document.getElementById('frax-results').scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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