FRAX (Fracture Risk Assessment Tool)
FRAX estimates the 10-year probability of a major osteoporotic fracture (hip, spine, forearm, humerus) and hip fracture specifically, using clinical risk factors with or without femoral neck BMD. Country-specific models are available for >70 countries.
inputs
✓ when to use
Use in adults aged 40–90 to assess fracture risk and guide osteoporosis treatment decisions. FRAX can be calculated with or without BMD — the clinical risk factor-only version is suitable for primary care screening. Add BMD (femoral neck T-score) when available for more precise estimation. Treatment thresholds are country-specific.
✗ when not to use
FRAX is for untreated patients — it is not validated for monitoring treatment response or for patients already on osteoporosis therapy. Does not capture falls risk (which independently affects fracture probability). Does not account for vertebral fracture number or recency (which significantly modify short-term risk). Not validated for glucocorticoid doses other than 'average' exposure.
clinical pearls
- FRAX can be used WITHOUT BMD as a first-line screening tool. If the clinical risk factor-only FRAX puts the patient above the treatment threshold, treatment can be initiated without DEXA. If the result is borderline, DEXA is warranted to refine the estimate.
- UK-specific FRAX intervention thresholds are published by NOGG (nogg.org.uk). The threshold varies by age — older patients have higher absolute risk thresholds for treatment because background fracture risk increases with age.
- The FRAX 'prior fracture' input has a major impact. Any prior fragility fracture (excluding skull, face, hands, feet) significantly elevates future fracture risk — this is the single most important clinical risk factor.
- FRAX uses 'average' glucocorticoid dose — it doesn't differentiate between prednisolone 2.5mg and 20mg daily. For high-dose glucocorticoid users, FRAX underestimates risk. The NOGG and FRAX websites offer glucocorticoid adjustment guidance.
- For patients with very recent vertebral fracture, the concept of 'imminent fracture risk' (high short-term risk) may justify treatment regardless of the 10-year FRAX result. FRAX captures long-term risk but may underestimate short-term risk in this scenario.