August 2, 2011
Details strengths and limitations of the tool,
provides recommendations for using surrogate country
models
FRAX® is a computer-based algorithm developed by the World
Health Organization Collaborating Centre for Metabolic Bone
Diseases to help predict the 10-year risk of fragility fracture.
Now with 34 specific country models, FRAX is being used
increasingly by physicians around the world to help assess their
patients’ fracture risk in the course of a clinical
assessment.
In a newly published review paper, the International Osteoporosis
Foundation (IOF) and the International Society for Clinical
Densitometry (ISCD) detail the findings of a joint Task Force that
met in November 2011 for the ‘ISCD IOF FRAX Initiative’
meeting. The objective was to make recommendations on how to
improve FRAX and better inform clinicians using the tool.
“FRAX is a widely accepted reference platform that allows
physicians to make more informed clinical assessments of their
patients. Nevertheless, they should be aware of the tool’s
limitations and take these into consideration when assessing
patients for further testing or pharmacological treatment,”
said Dr. Didier Hans, co-chair of the FRAX Initiative and immediate
past president of the ISCD. “Indeed, although FRAX scores
provide empirical evidence to better guide intervention, clinical
judgment is paramount.”
The review clarifies a number of important questions pertaining to
the interpretation and use of FRAX in clinical practice and
highlights both perceived strengths and limitations. It provides
details on the clinical risk factors currently used and explains
the reasons for the exclusion of other risk factors. Several of the
key issues discussed include:
Strengths:
- FRAX has been validated in 11 independent cohorts covering in
excess of 1 million patient years. The model determines the
predictive importance of each clinical risk factor, as well as
interactions between them, to optimize the accuracy of fracture
probability.
- FRAX models are based on country-specific data. Unlike more
simple risk models, the tool integrates mortality as well as
age-specific fracture rate statistics.
- FRAX is appreciated for its simplicity for use in primary care.
It is primarily used as a clinical tool to help physicians assess
fracture probability as an aid in identifying which individuals may
be candidates for reassurance, bone density evaluation or
pharmacological treatment. FRAX is also used for guideline
development, drug registration and health economic
applications.
- The tool is freely accessible online. As well, it is available
via iPhone, as a hand held calculator, and is integrated in
densitometry technology. It is available in 16 languages and a
growing number of country models (currently 40 models for 34
countries).
Limitations:
- FRAX does not take into account all risk variables of which the
physician should be aware. These include, for example, the risks
associated with falls, markers of bone turnover levels, other bone
density assessments, as well as certain secondary causes of
osteoporosis.
- For most clinical risk factors, FRAX uses yes/no answers and
the average risk is computed. It therefore does not take into
account the variation of risks associated with high or low doses of
glucocorticoids, the number and type of prior fractures, or the
quantity of alcohol or tobacco consumption.
- Other limitations of FRAX are dictated by the current
scientific evidence available. FRAX does not take into
consideration patients on treatment, younger men and women,
variations of fracture rates within countries and changes of
country-specific fracture rates over time.
In countries not yet included in FRAX, physicians may use surrogate
country models, preferably choosing a surrogate model country which
best approximates the fracture risk and death hazard of the index
country.
Professor Cyrus Cooper, chair of the IOF Committee of Scientific
Advisors and co-chair of the ISCD IOF FRAX Initiative, commented,
“FRAX represents a significant advance which has facilitated
the assessment of osteoporosis-related fracture risk to aid
clinicians in identifying high risk subjects. Given the widespread
use and interest in FRAX and its adoption in an increasing number
of management guidelines around the world, we must ensure that
clinicians worldwide are well informed and aware of best practice
in the use of this important new tool.”
Interpretation and use of FRAX in clinical practice. Osteoporos
Int. 2011.
DOI: 10.1007/s00198-011-1713-z. Available at http://www.springerlink.com/content/k4181054x0t88346/
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