Understanding the Who FRAX 10-year hip fracture probability score?

Millions of people worldwide face an increased risk of osteoporotic fractures as they age. To help healthcare providers and patients make informed decisions, the World Health Organization (WHO) developed the FRAX 10-year hip fracture probability score to quantitatively assess this risk.

Quick Summary

The WHO FRAX tool calculates your estimated 10-year probability of experiencing a hip fracture by integrating various clinical risk factors with or without bone mineral density (BMD) measurements, serving as a critical guide for identifying individuals who may need treatment. It helps healthcare providers target interventions to reduce fracture risk effectively.

Key Points

• FRAX Purpose: The WHO FRAX tool estimates a person's 10-year probability of a major osteoporotic fracture or a hip fracture specifically.

• Calculation Factors: The score is calculated using clinical risk factors like age, BMI, lifestyle habits, and medical history, with optional femoral neck BMD.

• Treatment Thresholds: In the U.S., a 10-year hip fracture probability of ≥3% is a common threshold for considering osteoporosis treatment.

• Target Audience: FRAX is primarily used for untreated, postmenopausal women and men aged 50 and older with osteopenia to guide treatment decisions.

• Not for Monitoring: The tool is not designed to monitor a patient's response to osteoporosis treatment over time.

• DXA vs. FRAX: A DXA scan measures bone density, whereas the FRAX tool incorporates the DXA result with other risk factors to provide a broader fracture risk probability.

What is the FRAX Tool?

The Fracture Risk Assessment Tool (FRAX) is an online calculation tool created by the World Health Organization (WHO) in 2008. Its main function is to predict a person's 10-year chance of having a major osteoporotic fracture (hip, spine, forearm, or shoulder) and specifically a hip fracture. The tool is based on data from population studies globally and is included in over 80 national guidelines. It is intended for use by primary care doctors to find patients at risk and guide treatment, especially for those with low bone density (osteopenia).

History and Development

FRAX was developed at the Centre for Metabolic Bone Diseases in the UK, in collaboration with international researchers. Before FRAX, fracture risk assessment mainly relied on bone density measurements from DXA scans. However, this method alone wasn't enough to capture all the factors influencing a person's risk. FRAX improved assessment by combining multiple clinical risk factors with or without bone mineral density data, offering a more complete picture.

How the FRAX 10-Year Probability is Calculated

The FRAX calculation uses 12 questions and, if available, femoral neck BMD, to estimate fracture probability. The tool requires input on personal and medical factors, including:

• Age (40-90 years)
• Sex
• Weight and height (for BMI)
• Past fracture history
• Parental hip fracture history
• Smoking status
• Use of oral glucocorticoids (3+ months)
• Rheumatoid arthritis diagnosis
• Secondary causes of osteoporosis
• Alcohol intake (3+ units daily)
• Femoral neck bone mineral density (BMD)

Using this information, the FRAX algorithm provides two 10-year probability scores: one for a major osteoporotic fracture and one for a hip fracture.

Interpreting Your Hip Fracture Probability Score

The FRAX score is given as a percentage, indicating the likelihood of a fracture in the next ten years. For hip fracture probability, treatment thresholds vary by country and guidelines. In the United States, the National Osteoporosis Foundation (NOF) often suggests considering treatment if the 10-year probability is 3% or higher. If your score is above this, your doctor may discuss treatment to lower your risk. Keep in mind, FRAX is a risk assessment tool, not a diagnosis, and treatment decisions should be made with a healthcare professional based on your overall health.

FRAX vs. DXA Scan: A Comparison

FRAX and DXA scans are complementary tools for assessing fracture risk. A DXA scan measures bone density, while FRAX uses this measurement along with clinical risk factors to calculate a probability score. The table below highlights their key differences:

Feature	FRAX Tool	DXA Scan
Purpose	Estimates 10-year fracture probability.	Measures bone mineral density (BMD).
Assessment Method	Questionnaire based on clinical risk factors.	Non-invasive X-ray scan.
Output	Percentage probability of fracture.	T-score and Z-score.
Input	Can be used with or without femoral neck BMD.	Primary source of BMD data for FRAX calculation.
Best Use Case	Initial risk assessment, especially for patients with osteopenia, to guide treatment decisions.	Confirmatory test for bone health and diagnosis of osteoporosis.

Limitations of the FRAX Tool

Healthcare providers need to be aware of several limitations when using and interpreting FRAX results. These include:

• Risk Factor Detail: FRAX uses simple 'yes/no' inputs for some risk factors like glucocorticoid use and smoking, not accounting for the dosage or duration, which can impact risk.
• Prior Fractures: It doesn't differentiate between one prior fracture and multiple prior fractures, despite the increased risk associated with more fractures.
• Treatment Status: FRAX is only validated for individuals who have not started pharmacological treatment for osteoporosis. It cannot track treatment effectiveness.
• Falls Risk: The standard FRAX tool does not directly incorporate the risk of falls, a significant factor in fractures.
• BMD Input: It only uses femoral neck BMD, not BMD from other sites like the spine, which might show different results.

What to Do with Your FRAX Score

Your FRAX score is a starting point for discussions with your healthcare provider. Your doctor will interpret the score within the context of your overall health and lifestyle. Potential next steps may include:

1. Discuss the Score: Understand what your hip fracture probability means for you.
2. Consider Lifestyle Changes: Address modifiable risks like smoking and alcohol, and discuss preventing falls.
3. Review Treatment Options: If your risk is high, medication to strengthen bones might be recommended.
4. Evaluate Further Testing: Additional tests may be needed based on your results.
5. Create a Personal Plan: Work with your doctor to develop a strategy for bone health and fracture prevention.

For more details on the official FRAX tool, visit the International Osteoporosis Foundation website https://www.osteoporosis.foundation/.

Conclusion

The WHO FRAX 10-year hip fracture probability score represents a significant advancement in assessing osteoporosis-related fracture risk. By incorporating multiple clinical factors alongside bone density, it offers a more comprehensive approach. This tool helps both patients and doctors make informed decisions about bone health and senior care. Despite its limitations, when used and interpreted correctly, FRAX is a valuable resource for preventing fractures and enhancing the lives of older adults.

Frequently Asked Questions

What is considered a high WHO FRAX 10-year hip fracture probability score?

A 10-year hip fracture probability of 3% or more is often considered a high-risk score that may warrant pharmacological treatment, according to guidelines from the National Osteoporosis Foundation. Your doctor will use this information, along with other factors, to determine the best course of action.

Does the FRAX tool replace a bone density test?

No, the FRAX tool does not replace a bone density test. A DXA scan measures your actual bone mineral density, while FRAX uses that data (if available) along with other clinical risk factors to calculate a more complete 10-year fracture probability. They work together to provide a comprehensive assessment.

Can I use the FRAX tool if I'm already on osteoporosis medication?

The standard FRAX tool is validated for use in individuals who have not received prior pharmacological treatment for osteoporosis. It cannot be used to monitor the effectiveness of therapy. If you are on treatment, your doctor will use other methods to assess your progress.

How accurate is the FRAX tool?

FRAX is a well-validated tool based on large population studies and is considered a strong predictor of major osteoporotic and hip fractures. However, it has limitations, such as not accounting for certain factors like multiple prior fractures or fall risk, so it should always be used in conjunction with a doctor's clinical judgment.

Why is my parental history of hip fracture a factor in my FRAX score?

A parental history of hip fracture is a significant independent risk factor for fracture. Genetic predisposition and shared lifestyle factors play a role in bone health, so incorporating this information helps to improve the accuracy of the FRAX calculation.

Can I improve my FRAX score?

Some factors used in the FRAX calculation are modifiable, such as smoking and alcohol consumption. Your doctor may also recommend lifestyle changes, like improving nutrition and increasing physical activity, to improve your overall bone health, though the score itself is a starting point for discussion rather than a metric to be directly 'improved'.

What is the difference between the 10-year hip fracture probability and the major osteoporotic fracture probability?

The FRAX tool provides two scores. The 10-year hip fracture probability is the risk for a fracture specifically at the hip. The major osteoporotic fracture probability includes the risk for a hip, clinical spine, forearm, or shoulder fracture. The hip fracture score is often a key indicator for determining treatment need.