FRAX Fracture Risk Calculator

FRAX Equation:

\[ FRAX(\%) = f(Age, Sex, Weight, Height, Previous\ fracture, Parent\ fractured\ hip, Current\ smoking, Glucocorticoids, Rheumatoid\ arthritis, Secondary\ osteoporosis, Alcohol, BMD) \]

Age:

years (40-90)

Sex:

Weight:

Height:

Previous Fracture:

Parent Fractured Hip:

Current Smoking:

Glucocorticoids:

Rheumatoid Arthritis:

Secondary Osteoporosis:

Alcohol 3+ units/day:

Femoral Neck BMD:

g/cm² (optional)

10-year Fracture Risk:

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1. What is the FRAX Tool?

The FRAX tool is a computer-based algorithm that calculates the 10-year probability of a major osteoporotic fracture (hip, clinical spine, humerus, or wrist fracture) and the 10-year probability of hip fracture. It was developed by the World Health Organization Collaborating Centre for Metabolic Bone Diseases.

2. How Does the Calculator Work?

The calculator uses the FRAX equation:

\[ FRAX(\%) = f(Age, Sex, Weight, Height, Previous\ fracture, Parent\ fractured\ hip, Current\ smoking, Glucocorticoids, Rheumatoid\ arthritis, Secondary\ osteoporosis, Alcohol, BMD) \]

Where:

Age — Between 40-90 years
Sex — Male or Female
Weight — Body weight in kg
Height — Height in cm
Previous fracture — Previous fragility fracture (yes/no)
Parent fractured hip — Parental history of hip fracture (yes/no)
Current smoking — Current tobacco smoking (yes/no)
Glucocorticoids — Current or past use of oral glucocorticoids (yes/no)
Rheumatoid arthritis — Diagnosis of rheumatoid arthritis (yes/no)
Secondary osteoporosis — Conditions associated with osteoporosis (yes/no)
Alcohol — Alcohol intake of 3 or more units/day (yes/no)
BMD — Femoral neck bone mineral density (optional)

Explanation: The algorithm combines clinical risk factors with or without femoral neck BMD to calculate fracture probability.

3. Importance of Fracture Risk Assessment

Details: FRAX provides an assessment of fracture risk that helps guide treatment decisions. It's particularly useful for identifying individuals at high risk who may benefit from pharmacological intervention.

4. Using the Calculator

Tips: Enter all required information accurately. BMD is optional but provides more accurate results when available. The calculator is valid for ages 40-90 years.

5. Frequently Asked Questions (FAQ)

Q1: What does the 10-year probability mean?
A: It represents the likelihood (as a percentage) that you will experience a major osteoporotic fracture in the next 10 years.

Q2: When is treatment recommended based on FRAX?
A: Treatment thresholds vary by country but generally consider intervention when 10-year major fracture probability exceeds 20% or hip fracture probability exceeds 3%.

Q3: How accurate is FRAX without BMD?
A: FRAX works well without BMD, though adding BMD improves accuracy, particularly in individuals near intervention thresholds.

Q4: Can FRAX be used for monitoring?
A: FRAX is designed for initial assessment, not monitoring. Reassessment after 2-5 years may be appropriate in untreated individuals.

Q5: Are there limitations to FRAX?
A: FRAX doesn't account for dose responses for some risk factors (e.g., glucocorticoid dose) or all risk factors for fracture.