Standards for Bone Mineral Density Testing

Backgrounder

The first international standards for bone mineral density (BMD) testing have been developed by Canadians and were recently published in The Journal of Clinical Densitometry.  A summary statement appears in the November 12th issue of the Canadian Medical Association Journal (CMAJ) in conjunction with the clinical practice guidelines for osteoporosis.

The standards establish the minimum level of quality acceptable in the performance of BMD.  The standards were based on a review of the densitometry literature and reflect the consensus of the Canadian Panel of the International Society for Clinical Densitometry (ISCD), which consists of leading experts in the field of bone disease and bone measurement from across Canada.  The standards were developed to ensure high quality BMD testing and reporting in Canada.

It is important to identify individuals with osteoporosis prior to the onset of fractures, as both vertebral and appendicular fractures are associated with an increased risk of subsequent fractures.1  Bone densitometry allows accurate and precise skeletal assessment, and enables detection of osteoporosis prior to the development of clinical fractures.

Key recommendations of the standards are:

• osteoporosis can be diagnosed with a DXA bone densitometer  assessing  the hip, spine, and forearm only
• using techniques such as ultrasound or other bone density machines at different locations such as the hand and the heel are not yet approved, and the diagnosis of osteoporosis cannot be made using these different technologies
• the bone density result has to be taken in addition to other important risk factors for fracture such as a prior fragility fracture, having a family history for an osteoporotic fracture, being of low body weight or being a smoker
• individuals who have other risk factors for fracture are at an increased risk for fracture, and this information must be considered with the bone density test
• BMD testing should only be completed if the results of the test will affect patient management.  For example, a woman experiencing menopause without risk factors of osteoporosis would not require routine BMD testing whereas a woman with a history of fragility fracture would require testing
• anyone over the age of 65, with or without other risk factors, should have a BMD test
• BMD testing should also be given to individuals with at least one major risk factor (i.e. family history of osteoporotic fracture or early menopause - before age 45), or two minor risk factors (i.e. low dietary calcium intake, excess alcohol or caffeine intake or past history of diseases associated with bone loss such as hyperthyroidism or hyperparathyroidism)
• to minimize error in the assessment, follow-up BMD measurements for a patient should be done on the same instrument with the same scanning procedure, and the same technologist
• in general, repeat BMD measurement can be considered after one year if there is a concern of rapid progressive bone loss, or every two to three years in individuals who started therapies that minimally increase BMD such as calcitonin and raloxifene, or who are stable or improving on drug therapies
• physicians and density labs need to adhere to these standards to ensure better scanning techniques and reporting

In addition, the standards clearly address how bone density testing should be done, how the results should be interpreted, and how they should be applied to the care of the patient. 

More specifically, these standards will help:

• physicians to identify which patients should receive a BMD test and which should not receive the test
• physicians to understand how the results of the test are used to determine a fracture
• technologists to position and scan the patient properly so the test is done accurately
• technologists to be aware of radiation safety and protection
• physicians to understand how accurate the test is and how much precision error is inherent in the study
• density labs to develop appropriate quality control standards to ensure that the machines are functioning accurately
• physicians to understand how to report the test, interpret it, and apply it in daily practice

DXA is a proven technology in the diagnosis and management of bone mineral loss and is now widely used across Canada.  Optimum benefit from this technology requires the maintenance of high standards in technical application, medical supervision, and interpretation of the results.

The new standards for BMD testing will ensure excellence in scanning, interpretation, reporting, and application of the results in daily clinical practice resulting in patient confidence and reassurance.  Patients will know that their BMD test has been done accurately and that their physician can correctly interpret the results and effectively treat their underlying bone disease.

References

1AA Khan, JP Brown, et al.  Summary and recommendations on performing central dual energy x-ray absorptiometry (DXA) from the Canadian Panel of the International Society for Clinical Densitometry.  

102-1117.

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