What is FRAX?
FRAX, which stands for Fracture Risk Assessment Tool, is a web-based platform launched in 2008 by the University of Sheffield. It was developed to evaluate an individual’s 10-year probability of fracture based on clinical risk factors and bone mineral density (BMD). The FRAX models were created using data from the WHO Collaborating Centre for Metabolic Bone Diseases, although the tool itself was not developed or endorsed by the World Health Organization.
The FRAX web platform provides users with the ability to create an individualized account to store their fracture risk calculations. A beta-version of the site also offers fee-based access to modified FRAX probabilities.
Development of the FRAX Tool
The FRAX tool was developed by researchers at the University of Sheffield in collaboration with the WHO Collaborating Centre for Metabolic Bone Diseases. The models used in FRAX were created by studying population-based cohorts from various regions worldwide, including:
- Europe
- North America
- Asia
- Australia
The aim was to create a tool that could accurately predict fracture risk by integrating multiple clinical risk factors along with bone mineral density measurements.
FRAX Web Platform
The FRAX website (www.fraxplus.org) offers users several key features:
- The ability to create an individualized FRAX account to store fracture risk calculations
- A beta-version with fee-based access to modifications of the standard FRAX probability output
The web platform provides a convenient and accessible way for healthcare professionals and individuals to assess fracture risk using the FRAX tool.
How Does FRAX Work?
The FRAX tool calculates an individual’s 10-year probability of fracture by integrating information on clinical risk factors and bone mineral density (BMD). The models used in FRAX were developed from studying population-based cohorts worldwide, ensuring their applicability to a wide range of individuals.
Clinical Risk Factors Evaluated by FRAX
The clinical risk factors considered by FRAX include:
| Risk Factor | Description |
|---|---|
| Age | Between 40 and 90 years (defaults to 40 or 90 if outside this range) |
| Previous fracture | Spontaneous or trauma-induced fractures in healthy individuals |
| Oral glucocorticoids exposure | ≥ 3 months at prednisolone dose of ≥ 5mg daily or equivalent |
| Disorders associated with osteoporosis | Diabetes, osteogenesis imperfecta, hyperthyroidism, hypogonadism, premature menopause, malnutrition, malabsorption, chronic liver disease |
| Alcohol consumption | ≥ 3 units daily (equivalent to standard alcohol measures) |
Other factors like rheumatoid arthritis (RA) and body mass index (BMI) are also considered. Interestingly, while RA is a risk factor for fracture, osteoarthritis appears to be protective.
Bone Mineral Density (BMD) in FRAX
BMD measurements, typically obtained using DXA scanning equipment, can be entered into FRAX to refine fracture risk assessments. The femoral neck BMD is the preferred site for input. FRAX expresses BMD as a T-score, which compares an individual’s BMD to the average value for young, healthy adults. The NHANES reference values for women aged 20-29 years are used, with the same values applied to men.
What Does FRAX Assess?
The FRAX tool provides an assessment of an individual’s 10-year probability of two types of fractures:
- Hip fracture
- Major osteoporotic fracture (clinical spine, forearm, hip, or shoulder fracture)
Hip Fracture
A 10-year probability of hip fracture ≥ 3% is considered significant. Hip fractures are associated with substantial morbidity, mortality, and healthcare costs.
Major Osteoporotic Fracture
A 10-year probability of major osteoporotic fracture ≥ 20% is deemed clinically relevant. Major osteoporotic fractures include those of the clinical spine, forearm, hip, and shoulder. These fractures can lead to pain, disability, and reduced quality of life.
Advantages and Limitations of FRAX
While FRAX is a valuable tool for fracture risk evaluation, it is essential to understand its strengths and limitations in clinical application.
Advantages of FRAX
- Integrates multiple clinical risk factors to provide a comprehensive fracture risk assessment
- Developed using data from diverse population-based cohorts worldwide
- Easily accessible through a web-based platform
Limitations of FRAX
- Does not account for dose-response relationships for some risk factors (e.g., glucocorticoid exposure)
- May underestimate fracture risk in the presence of certain conditions, such as vertebral fractures
- Relies on population-based data, which may not fully capture individual variations in fracture risk
Despite these limitations, FRAX remains a widely used and validated tool for fracture risk assessment in clinical practice.
Research and Validation of FRAX
The development of FRAX involved extensive research and collaboration among international experts in the field of metabolic bone diseases. Key researchers who contributed to the development and validation of FRAX include:
| Kanis JA | Oden A | Johnell O | Johansson H |
| De Laet C | Brown J | Burckhardt P | Cooper C |
| Christiansen C | Cummings S | Eisman JA | Fujiwara S |
| Glüer C | Goltzman D | Hans D | Krieg MA |
Numerous meta-analyses and validation studies have been conducted to assess the performance of FRAX in predicting fracture risk across different populations. Organizations such as the International Musculoskeletal Ageing Network have also contributed to the ongoing research and refinement of the FRAX tool.
In conclusion, FRAX is a valuable tool for assessing fracture risk by integrating clinical risk factors and bone mineral density. While it has some limitations, its development and validation through extensive research have established its utility in clinical practice. As research in the field of metabolic bone diseases continues, the FRAX tool may undergo further refinements to enhance its predictive capabilities.
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