What’s your future risk of fracture? Find out with FRAX

Fracture risk ahead
The popular online tool to calculate 10-year risk of osteoporotic fracture should be part of any bone health assessment.

A bone mineral density (BMD) test result is the benchmark used to diagnose osteoporosis and is one of the strongest predictors of future fracture risk. But the density of your bones alone is not the only predictor of fracture risk. In fact, while people with low BMD are at greater risk of fracture than those with normal BMD, the greatest number of fractures occur in  people who have BMD values above the commonly used ‘osteoporosis’ diagnostic threshold of -2.5 SD. See diagnosis. That’s because when it comes to fragility fractures, there are many factors in addition to low BMD which can affect your risk. A similar example is high blood pressure – although it is a significant warning sign that you are at higher risk of cardiovascular disease, there are other important factors which also affect your personal risk of suffering a stroke.

What is FRAX?

To improve the identification of people at high risk of fracture, a World Health Organization (WHO) task force developed an online calculator that first came into use in 2008. This tool, called FRAX® (short for Fracture Risk Assessment Tool) calculates an individual’s risk of having an osteoporotic fracture within the next ten years, based on specific risk factors.

FRAX was developed in order to provide doctors with a way to better identify which patients are at high risk of fracture. Because the calculator can also be used without BMD values, FRAX is a vailable tool in locations around the world where doctors and patients may not have ready access to bone mineral density testing facilities.

The risk factors that are included in the calculator are those which researchers have scientifically analysed (‘validated’) as contributing to osteoporotic fracture risk, over and above the risk determined by BMD and age. The calculator is designed for use in individuals aged 40 to 90 years who are not already receiving osteoporosis therapy. It is country-specific because it incorporates data about mortality and fracture risk that are specific to each individual country.

FRAX is available as a free online tool on the Sheffield University website (FRAX calculator). Since 2011 the online calculator has been used to assess more than 10.3 million people – and its use is growing steadily as more and more country calculators become available. Currently FRAX is available for 57 countries, with separate calculators for different ethnicities in the USA. It can be used in 30 different languages.

Which risk factors are included in FRAX?

The information the calculator requires is the following:

  • Which country you live in (be sure to select your country as the first step)
  • Your age
  • Your gender
  • Your body mass index (calculates this from your weight and height)
  • Your bone mineral density (optional)

It also asks for a ‘yes’ or ‘no’ for these clinical risk factors:

  • Previous fracture
  • Whether your parent has fractured a hip
  • Current smoking
  • Glucocorticoid use (drugs such as prednisone)
  • Rheumatoid arthritis
  • Secondary osteoporosis (refers to disorder strongly associated with osteoporosis such as type I insulin dependent diabetes, osteogenesis imperfecta in adults, untreated long-standing hyperthyroidism, hypogonadism or premature menopause before age 45, chronic malnutrition, or malabsorption and chronic liver disease)
  • Alcohol intake of 3 units or more per day

FRAX calculation tool

Interpreting FRAX results

After you complete the calculation the result will show your 10-year probability (in %) of any major osteoporotic fracture and of a hip fracture. The same person would have different fracture probabilities depending on the country-model used. For example, a 58 year-old woman who weighs 70 kilos, is 168 cm tall, and smokes (but has no other FRAX risk factors) would have the following risks for major osteoporotic and hip fracture respectively:

For UK – 5.7% and 0.9%
For Japan – 5.0% and 0.5%
For Argentina – 2.8% and 0.6 %

The UK (along with Lebanon and Finland) calculator is one of the few that also provides guidance based on national recommendations. If living in the UK, this woman’s result would include NOGG interpretation guidance as follows:

FRAX assessment threshold

The x’ is plotted in the green area which indicates that it may be sufficient to simply give this patient lifestyle advice to help prevent bone loss. However, FRAX results are meant as an aid within the scope of a clinical assessment. In this case the doctor could very well end up recommending BMD testing on the basis of other factors. It should be noted that recommendations vary from country to country. 

FRAX is only one piece of the puzzle – a complete clinical assessment is needed

While the calculator is easy for anyone to use, FRAX results should be ‘interpreted’ by your doctor and assessed within the course of a complete bone health check-up. The decision to treat, or not to treat, is not only personal, but as mentioned above, one that depends on the osteoporosis management recommendations in your country. Before any treatment recommendation is made you would also be assessed (often using lab tests) for other bone health determinants such as diseases or medications that could contribute to bone loss, nutritional status, possible falls risk, and lifestyle factors that contribute to poor bone and muscle health. 

FRAX has certain limitations and this means that your doctor will have to use good clinical judgement when interpreting results. For example, although FRAX asks whether you take corticosteroids, it doesn’t ask how much, or how long. Adjustments would have to be made when interpreting your results, based on whether you had been taking high quantities of corticosteroids over a long period of time or small quantities over less than three months. Another example is previous fracture – what is meant here is a fragility fracture as an adult (for example, a broken wrist as a result of a fall from standing height), rather than a broken bone sustained at age 16 in a high-trauma sporting accident. Fracture probability would also be underestimated in someone who has suffered multiple fragility fractures.

Ask for a FRAX calculation if available for your country

If you’re aged over 50 or have reason to believe that you may be at risk, ask for a FRAX assessment during your next physical check-up. The FRAX results will give your doctor a more complete picture of your bone health status and provide the important additional information about fracture risk that is needed to make any informed treatment decision.

LYB logoThis article appeared in our monthly Love Your Bones newsletter sent to IOF members.

Not yet an IOF member? Join today - it's free!