FRAX Tool: When to Use and Treatment Thresholds
Use the FRAX calculator in adults aged 40 years or older with osteopenia (T-score between -1.0 and -2.5) to determine who needs pharmacologic treatment; treat when 10-year hip fracture risk is ≥3% or major osteoporotic fracture risk is ≥20%. 1
When to Use FRAX
FRAX should be applied in the following clinical scenarios:
- Adults ≥40 years with osteopenia (T-score between -1.0 and -2.5) to determine treatment necessity 1
- Postmenopausal women and men ≥50 years who have not yet had DXA scanning but have clinical risk factors 1
- Glucocorticoid-treated patients ≥40 years for risk stratification (with GC dose adjustment) 2
Do NOT use FRAX in:
- Patients already diagnosed with osteoporosis (T-score ≤-2.5) - they already meet treatment criteria 1
- Patients with prior fragility fractures - they already qualify for treatment 1
- Adults <40 years - FRAX is not validated in this age group 3, 4
- Patients already on osteoporosis treatment - FRAX is only validated for untreated patients 5
U.S. Treatment Thresholds
Pharmacologic therapy is strongly recommended when: 1, 6
Hip Fracture Risk
- ≥3% 10-year probability
Major Osteoporotic Fracture Risk
- ≥20% 10-year probability
These thresholds apply to adults aged 40 years or older with T-scores between -1.0 and -2.5. Major osteoporotic fracture includes clinical spine, hip, wrist, or humerus fractures 1.
FRAX Input Requirements
The calculator incorporates these clinical risk factors 1:
- Age and sex
- Body mass index (BMI) or height/weight
- Prior fragility fracture
- Parental history of hip fracture
- Current smoking
- Glucocorticoid use (≥3 months at ≥5mg prednisone daily)
- Rheumatoid arthritis
- Secondary osteoporosis causes
- Alcohol intake (≥3 units daily)
- Femoral neck BMD (optional but improves accuracy) 1, 4
Special Considerations for Glucocorticoid Users
For patients on glucocorticoids >7.5 mg/day prednisone equivalent, adjust FRAX upward: 2
- Multiply major osteoporotic fracture risk by 1.15
- Multiply hip fracture risk by 1.2
Example: If calculated hip fracture risk is 2.0%, increase to 2.4% (2.0 × 1.2).
Risk Stratification Categories
Very High Risk (requires most aggressive treatment) 1
- Prior osteoporotic fracture
- FRAX major osteoporotic fracture ≥30% OR hip fracture ≥4.5%
- T-score <-3.0
- Recent fracture (within 12 months)
- Fractures while on osteoporosis therapy
High Risk 1
- T-score ≤-2.5
- FRAX major osteoporotic fracture ≥20% OR hip fracture ≥3%
Moderate Risk 1
- FRAX major osteoporotic fracture 10-19% OR hip fracture >1% to <3%
Important Caveats
FRAX underestimates risk in: 1
- Patients with multiple prior fractures (only counts as "yes/no")
- Recent fractures (within past 2 years)
- Lumbar spine BMD much lower than femoral neck BMD
- Patients with high fall risk (falls not directly captured)
- Certain secondary causes of osteoporosis
For patients with recurrent falls, consider using the Garvan fracture risk calculator as an adjunct 1.
FRAX accuracy varies by age: 7
- May underestimate risk in younger patients (40-60 years)
- May overestimate risk in older patients (>70 years)
- Including BMD improves accuracy, especially for hip fracture prediction 4, 7
Clinical Algorithm
Obtain DXA in women ≥65 years, men ≥70 years, or younger adults with risk factors 1
If T-score ≤-2.5 or prior fragility fracture: Treat immediately - FRAX not needed 1
If T-score between -1.0 and -2.5: Calculate FRAX 1
- Include femoral neck BMD for better accuracy
- Adjust for glucocorticoid dose if applicable
If FRAX ≥ thresholds (hip ≥3% OR major osteoporotic ≥20%): Initiate pharmacologic therapy 1
If FRAX below thresholds: Optimize calcium/vitamin D, lifestyle modifications, reassess in 1-2 years 1
The evidence strongly supports using these specific numeric thresholds rather than clinical gestalt alone, as approximately 48% of hip fractures and 56% of major osteoporotic fractures occur in patients with osteopenia rather than osteoporosis 8. This makes risk stratification with FRAX essential for identifying the subset of osteopenic patients who will benefit most from treatment.