Position Development PaperOfficial Positions for FRAX® Bone Mineral Density and FRAX® Simplification: From Joint Official Positions Development Conference of the International Society for Clinical Densitometry and International Osteoporosis Foundation on FRAX®
Introduction
FRAX® is a fracture risk assessment algorithm developed by the World Health Organization (WHO) to estimate the 10-year probability of hip fracture and major osteoporotic fracture (hip, clinical vertebral, proximal humerus, distal forearm) in untreated men and women from the age of 40 to 90 years. The input for FRAX is demographic patient information (age, sex, height, weight, and in the US only, one of 4 ethnicities) and femoral neck bone mineral density (BMD), when available. The output of FRAX can be used with clinical guidelines to aid in the selection of patients for starting pharmacological therapy to reduce fracture risk. The use of FRAX in clinical practice has raised concern that FRAX may underestimate or overestimate fracture risk in some patients, and raises the question of whether adjustments to the FRAX algorithm might improve the accuracy of fracture prediction or simplify the ease of use. To address such issues, the International Society for Clinical Densitometry (ISCD), in cooperation with the International Osteoporosis Foundation (IOF), convened the FRAX Position Development Conference (PDC) in Bucharest, Romania, on November 14, 2010. The topics considered at the PDC included the use of lumbar spine or distal 1/3 (33%) radius BMD for FRAX input as an alternative to femoral neck BMD, the use of quantitative ultrasound (QUS) of the heel instead of femoral neck BMD, and methods for simplifying the use of FRAX in clinical practice.
FRAX currently allows for the input of BMD for only the femoral neck measured by dual-energy X-ray absorptiometry (DXA), whereas the ISCD recommends that the diagnosis of osteoporosis in clinical practice be made according to the lowest DXA-measured T-score of the lumbar spine, total hip, femoral neck, or distal 1/3 (33%) radius, if measured. In some patients, the femoral neck BMD value may not be valid (e.g., structural abnormalities, surgical hardware) or measurable (e.g., the patient's weight exceeds the weight limit of the table, the patient is unable to be placed on the table due to disability), and in others the BMD at other skeletal sites, particularly the lumbar spine, may be much lower than at the femoral neck, suggesting that FRAX may underestimate fracture risk in such individuals. ISCD Official Positions were developed to address the use of lumbar spine and distal 1/3 radius BMD to predict fracture risk and whether these skeletal sites should be included in the FRAX algorithm.
FRAX is a validated tool to predict fracture risk using an input of clinical risk factors without femoral neck BMD. This is particularly useful when DXA is not available, accessible, or affordable. However, fracture risk prediction is improved when clinical risk factors are combined with BMD. In world regions where DXA measurements cannot be easily obtained, QUS is a potential alternative. QUS devices are less expensive than DXA, use no radiation, and are portable. Limitations of QUS include inability to diagnose osteoporosis with the WHO criteria, which are based on DXA-derived T-scores, and poor utility for monitoring patients treated for osteoporosis. The potential use of QUS-measured parameters of the heel for assessment of fracture risk and inclusion with FRAX was addressed at the PDC.
For the busy clinician, a simplified version of FRAX might make it more likely to be used when time and resources are limited. The utility of FRAX without BMD was evaluated, and the circumstances under which it might be appropriate to use FRAX without BMD were assessed. The evidence regarding the robustness of each of the FRAX risk factors in predicting fracture risk was evaluated, and the possibility of using fewer clinical risk factors was considered. The potential use of adding an additional risk factor, the rate of bone loss, was discussed.
All Official Positions were rated by the Expert Panel in three categories: quality of the evidence, strength of the evidence, and applicability.
Section snippets
Methodology & Data sources
Each task force subgroup performed a comprehensive review of the medical literature following PubMed searches using appropriate keywords for each topic question. Based on the findings of the reviews, preliminary Official Positions were developed and presented to the Expert Panel for consideration. All Official Positions for the 2010 PDC were rated by the Expert Panel in the following categories according to predefined criteria derived from the RAND/UCLA Appropriateness Method (RAM). Preliminary
BMD at Skeletal Sites other than Femoral Neck for FRAX Input
Questions: Can lumbar spine BMD and/or T-score be used to assess fracture risk with FRAX? Can lumbar spine BMD be used to assess vertebral, hip, major or any osteoporotic and any clinical fracture risk? Should lumbar spine T-score be used to assess fracture risk with FRAX? Should lumbar spine BMD be used to assess fracture risk with FRAX when the lumbar spine T-score is lower than the femoral neck T-score? Can lumbar spine BMD be used to assess fracture risk with FRAX when femoral neck BMD cannot be measured
QUS of the Heel FRAX Input
Questions: Can QUS of the calcaneus be used to assess fracture risk with FRAX? Can QUS-measured parameters (SOS, BUA, SI) of the calcaneus be used to assess vertebral, hip and any clinical fracture risk? Can QUS-measured parameters (SOS, BUA, SI) of the calcaneus be used to assess major and any osteoporotic fracture risk? Should QUS of the calcaneus T-score be used to assess fracture risk with current FRAX? Can QUS-measured parameters (SOS, BUA, SI) of the calcaneus be used to assess fracture risk with
Simplification of FRAX
Questions: How useful is FRAX without BMD? What are the circumstances when it is appropriate to use FRAX without BMD? What are the circumstances when it is not appropriate to use FRAX without BMD
Could a clinically useful simplified FRAX model be developed?
- xiv.
Which of the FRAX risk factors are the strongest predictors of fracture risk?
- xv.
Which of the FRAX risk factors are the weakest predictors of fracture risk?
- xvi.
What is the effect of excluding the weaker FRAX risk factors on assessment of fracture risk?
- xvii.
Is there a
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