The FRAX tool, developed by the World Health Organization (WHO), combines clinical risk factors with or without femoral neck bone mineral density (BMD) to estimate an individual's 10-year fracture probability. This estimate helps healthcare providers make informed decisions about when to start osteoporosis treatment. While FRAX provides valuable data, it is not the sole determinant for treatment, and other factors should be considered.
Understanding the FRAX Tool and its Role in Treatment Decisions
FRAX integrates several clinical risk factors that influence fracture risk independently of BMD. By combining these factors, FRAX provides a more comprehensive assessment than BMD alone, particularly for patients with osteopenia, or low bone mass. This is important because many fractures occur in individuals with BMD T-scores above the osteoporosis threshold (T-score < -2.5).
How FRAX guides treatment for osteopenia
For patients with a T-score in the osteopenic range (-1.0 to -2.5), FRAX is used to determine if their 10-year fracture risk warrants pharmacological treatment. The internationally recognized thresholds for treatment are:
- A 10-year hip fracture probability of $\ge$3%.
- A 10-year probability of a major osteoporotic fracture of $\ge$20%.
These thresholds, adapted by guidelines in the United States by organizations such as the Bone Health and Osteoporosis Foundation (BHOF, formerly NOF), are based on cost-effectiveness studies and clinical evidence. The calculated risk is a guideline and should be considered alongside other clinical factors.
Other indicators for initiating osteoporosis treatment
It is crucial to note that a high FRAX score is not the only reason to start treatment. Other scenarios that may trigger the initiation of therapy, regardless of the FRAX calculation, include:
- A prior hip or vertebral (spine) fracture.
- A BMD T-score of $\le$-2.5 at the femoral neck or spine.
- Use of high-dose glucocorticoids.
For patients already on osteoporosis medication, FRAX is not intended to be used for monitoring treatment effectiveness or risk assessment.
A comparison of FRAX-based treatment guidelines
Several clinical guidelines provide criteria for initiating osteoporosis treatment using FRAX, although specific thresholds can vary by country and organization. Here is a comparison of two prominent examples:
| Feature | BHOF (formerly NOF, United States) | NOGG (United Kingdom) |
|---|---|---|
| Application | Use for postmenopausal women and men $\ge$50 with T-scores between -1.0 and -2.5. | Uses age-dependent intervention thresholds, making the decision more dynamic with age. |
| Key Thresholds | 10-year hip fracture risk $\ge$3%. 10-year major osteoporotic fracture risk $\ge$20%. |
Age-specific thresholds are used. For example, the intervention threshold may be lower at older ages. |
| BMD Integration | Incorporates BMD at the femoral neck. | Recommends DXA scan for those in the intermediate risk category to refine risk assessment. |
| Standalone Risk Factor | Prior hip or vertebral fracture and a T-score of $\le$-2.5 are direct indications for treatment, independent of FRAX. | Prior fragility fracture is a direct indication for treatment, independent of the initial FRAX calculation. |
How to get your FRAX score
The FRAX tool is available online and can be completed by a healthcare provider. The calculator requires input on a number of clinical risk factors, including:
- Age and gender: The foundation of the risk calculation.
- BMI (Body Mass Index): Used to assess weight-related risk.
- Prior fracture history: A previous fracture significantly increases future risk.
- Parental hip fracture: A strong indicator of genetic predisposition.
- Use of glucocorticoids: Long-term steroid use is a major risk factor.
- Secondary osteoporosis: Conditions like rheumatoid arthritis affect bone health.
- Smoking and alcohol use: Lifestyle factors that contribute to bone loss.
- Femoral neck BMD (optional but recommended): A dual-energy X-ray absorptiometry (DXA) scan at the femoral neck provides crucial data to refine the risk assessment.
Conclusion
The FRAX tool has revolutionized the approach to osteoporosis treatment by providing a more holistic view of an individual's fracture risk beyond just BMD. The key FRAX thresholds for initiating treatment in patients with osteopenia are a 10-year hip fracture risk of $\ge$3% or a major osteoporotic fracture risk of $\ge$20%. However, patients with a prior hip or vertebral fracture or a BMD T-score of $\le$-2.5 are generally recommended for treatment regardless of their FRAX score. Ultimately, the decision to start osteoporosis treatment should be made in consultation with a healthcare provider, who can combine the FRAX results with a comprehensive clinical evaluation to develop a personalized care plan.
For more information on the Fracture Risk Assessment Tool, you can visit the official FRAX website.
