24 July 2017:
Since its launch in 2008, the web-based fracture risk assessment tool FRAX®  has been evaluated thoroughly in additional validation studies and widely published in meta-analyses and clinical review papers. Furthermore, its predictive and discriminative powers have been compared with other osteoporotic fracture risk prediction tools . Two recent papers elucidate different aspects of the tool, one assessing its diagnostic accuracy in women and men from five different non-US populations , the other one calculating the time to 'clinically relevant' risk scores in US postmenopausal women , and both using the 10-year intervention thresholds of 20% for major osteoporotic fractures (MOF) and 3% for hip fractures (HF), as suggested by the National Osteoporosis Foundation (NOF) .
In the first paper, a systematic review and meta-analysis of seven studies from New Zealand, Canada, the USA, France and Poland, which tested FRAX® in populations other than the derivation cohorts, the tool 'performed better in identifying patients who will not have a MOF or HF within 10 years, than those who will. A substantial number of patients who developed fractures, especially MOF within 10 years of follow-up, were missed by the baseline FRAX® assessment', as stated by the authors in their conclusion.
For MOF prediction, the mean sensitivity, specificity, and diagnostic odds ratio (DOR) along with their 95% confidence intervals (CI) were 10.25% (3.76–25.06%), 97.02% (91.17–99.03%) and 3.71 (2.73–5.05); for HF prediction 45.70% (24.88–68.13%), 84.70% (76.41–90.44%) and 4.66 (2.39–9.08), respectively, the latter one being less precise because of its larger confidence region.
FRAX® is freely available and easy to use, not least because of its condensed and time-saving features. But this is at the expense of its sensitivity. Tools with a larger number of clinical risk factors, e.g. QFracture®, may be more sensitive but less feasible . Lowering the intervention threshold may also improve sensitivity but increase over-treatment .
The second paper estimates the timing of occurring ‘clinically relevant’ scores, i.e. treatment-level FRAX® scores, according to 2014 National Osteoporosis Foundation guidelines , and screening-level FRAX® scores, according to 2011 US Preventive Services Task Force (USPSTF) guidelines , in postmenopausal women of the Women’s Health Initiative (WHI) cohort.