FRAX Calculator Access and Usage
Access the FRAX calculator online at www.shef.ac.uk/FRAX or https://www.shef.ac.uk/FRAX/tool.jsp 1, 2, 1, 2, 3. This is a free, web-based tool developed by the WHO Sheffield Collaborating Centre that calculates 10-year fracture probability using easily obtainable clinical information.
How to Use FRAX for Your Patient
Required Inputs
Enter the following information into the online calculator 1, 4:
Mandatory fields:
- Age (40-90 years)
- Sex
- Weight and height (to calculate BMI)
Clinical risk factors (yes/no):
- Prior fragility fracture (after age 50)
- Parental history of hip fracture
- Current smoking status
- Glucocorticoid use (≥5 mg prednisone daily for ≥3 months)
- Rheumatoid arthritis
- Secondary osteoporosis (other causes)
- Alcohol intake (≥3 units/day)
Optional but recommended:
Important Note About Your Patient's Data
For the lumbar spine T-score of -2.2: FRAX uses femoral neck BMD, not lumbar spine values 1. You'll need the femoral neck measurement if available. FRAX can still calculate risk without any BMD input, though accuracy is reduced 4, 5.
For bisphosphonate use: FRAX is validated only for untreated patients 6. If your patient is currently on bisphosphonates, FRAX may not accurately reflect their current fracture risk.
For eGFR >35 mL/min: This doesn't directly enter into FRAX but may qualify as "secondary osteoporosis" if causing bone disease 1.
Glucocorticoid Dose Adjustment
Critical adjustment needed 2: Standard FRAX assumes prednisone 2.5-7.5 mg/day. If your patient takes >7.5 mg/day:
- Multiply the major osteoporotic fracture risk by 1.15
- Multiply the hip fracture risk by 1.2
For example: If FRAX shows 10% major fracture risk and 2% hip fracture risk with >7.5 mg/day prednisone, adjust to 11.5% and 2.4% respectively 2.
Interpreting Results
FRAX provides two outputs 1, 4:
- 10-year probability of hip fracture
- 10-year probability of major osteoporotic fracture (hip, clinical spine, humerus, or forearm)
US Treatment Thresholds
Consider pharmacologic treatment if 1:
- 10-year hip fracture risk ≥3%, OR
- 10-year major osteoporotic fracture risk ≥20%
These thresholds apply to postmenopausal women and men ≥50 years with osteopenia (T-score -1.0 to -2.5) 1.
Critical Limitations to Recognize
FRAX underestimates risk in patients with 1:
- Multiple prior fractures (only counts yes/no, not number)
- Recent fractures (doesn't account for timing)
- Lumbar spine BMD much lower than femoral neck
- History of falls (not captured in the tool)
- Vertebral fractures specifically
For patients with fall history: Consider using the Garvan fracture risk calculator (www.fractureriskcalculator.com) as a complementary tool, though it's based on less extensive data 1, 3.
Country-Specific Versions
Select the appropriate country version when accessing FRAX, as fracture incidence varies geographically 4, 7. The US version has race/ethnicity-specific calculators (White, Black, Asian, Hispanic), though concerns exist about their validity in creating treatment disparities 7.
Integration with DXA Software
Many DXA machines now have FRAX integrated directly into their reporting software following FDA approval, allowing automatic calculation when BMD is measured 7, 8.