Background
Worldwide there is great interest in assisting in clinical decision making by improving the assessment of actual individual future risk of fracture. This new initiative uses similar methodology to the Framingham cardiovascular risk calculator to calculate the risk of fracture, expressed as a percentage over the next five to ten years.
Calculators
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Background
Worldwide there is great interest in assisting in clinical decision making by improving the assessment of actual individual future risk of fracture. This new initiative uses similar methodology to the Framingham cardiovascular risk calculator to calculate the risk of fracture, expressed as a percentage over the next five to ten years. Osteoporosis Australia considers that the risk calculators, which can be accessed from this web site, are a step forward in assisting in clinical decision making, when used in addition to the current treatment threshold approach. The threshold model uses a DXA BMD T score of -2.5 the BMD selected by the WHO as indicative of osteoporosis, or in some patient’s with risk factors a T score of -1.5, as indicators of when therapy for osteoporosis is appropriate. The use of the risk calculators poses the question of “What level of risk of fracture should patients undertake treatment that itself may have risks and costs.”
Current PBS Rules
The PBS rules for receiving a federal government subsidy for pharmaceutical treatment do not currently use a risk calculator approach. Instead, the following criteria must be met:
- A minimal trauma fracture, or
- A male or female over 70 with a T score of -3.0 or less (five year fracture risk about 10-20%), or
- Be receiving the equivalent of 7.5 mg of prednisone or equivalent for more than 3 months and have a T score of -1.5 or less.
Suggested Risk Levels for Intervention
In addition to the above PBS rules, Osteoporosis Australia also suggests that the following levels of risk should be considered in advising patients on treatment:
| Low risk |
less that 8% five year risk for any fracture and 3% risk for hip fracture |
lifestyle intervention (diet and exercise) |
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Moderate risk |
greater than 8% five year risk for any fracture and 3% risk for hip fracture |
advise pharmacological treatment in addition to lifestyle interventions, especially if the Government will provide a rebate |
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High risk |
greater than 15% 5year risk for any fracture especially spine fracture |
strongly advise pharmaceutical therapy in addition to lifestyle interventions |
Please note these suggested levels of risk for intervention are interim prior to development of a comprehensive position statement.
The decision to use pharmacological treatments should generally be restricted to patients with low DXA BMD. This is because pharmaceutical treatments available in Australia have all been proven in randomised controlled trials in which the patients were selected by DXA BMD to have low bone density (usually T score less than -2.0), apart from prednisone use where the threshold has been raised to -1.5).
Notes on use of the risk calculators
There are a variety of risk calculators which use different models and different assumptions; consequently, there are different estimates of fracture risk. When using a risk calculator in Australia, it is recommended that clinicians should use the patient’s hip DXA bone density (either the femoral neck or the total hip, depending on the calculator) rather than T score.
In the case of the FRAX calculator, no specific calculator has been developed for Australia, the use of UK or US data results in substantial variation in the calculated risk.
Finally, as those who try to predict financial markets know, predicting the future may result in substantial errors, fracture risk calculators are no different.
