FRAX vs CAROC for the Canadian Imaging Physician: An Existential Dilemma

Risk assessment tools for osteoporosis and fractures in 2022

Osteoporosis is one of the frequently encountered non-communicable diseases in the world today. Several hundred million people have osteoporosis, with many more at risk. The clinical feature is a fragility fracture (FF), which results in major reductions in the quality and quantity of life, coupled with a huge financial burden. In recognition of the growing importance, the World Health Organisation established a working group 30 years ago tasked with providing a comprehensive report to understand and assess the risk of osteoporosis in postmenopausal women. Dual-energy X-ray absorptiometry (DXA) is the most widely endorsed technology for assessing the risk of fracture or diagnosing osteoporosis before a fracture occurs, but others are available. In clinical practice, important distinctions are essential to optimise the use of risk assessments. Traditional tools lack specificity and were designed for populations to identify groups at higher risk using a 'one-size-fits-all' approach. Much has changed, though the purpose of risk assessment tools remains the same. In 2022, many tools are available to aid the identification of those most at risk, either likely to have osteoporosis or suffer the clinical consequence. Modern technology, enhanced imaging, proteomics, machine learning, artificial intelligence, and big data science will greatly advance a more personalised risk assessment into the future. Clinicians today need to understand not only which tool is most effective and efficient for use in their practice, but also which tool to use for which patient and for what purpose. A greater understanding of the process of risk assessment, deciding who should be screened, and how to assess fracture risk and prognosis in older men and women more comprehensively will greatly reduce the burden of osteoporosis for patients, society, and healthcare systems worldwide. In this paper, we review the current status of risk assessment, screening and best practice for osteoporosis, summarise areas of uncertainty, and make some suggestions for future developments, including a more personalised approach for individuals.

Comparison of 2 fracture risk estimation processes in Alberta: a cross-sectional chart review

BACKGROUND

In Canada, decisions regarding osteoporosis pharmacotherapy are based on estimated 10-year risk of osteoporotic fracture. We aimed to determine how frequently 2 common approaches (Canadian Association of Radiologists and Osteoporosis Canada [CAROC] tool and Fracture Risk Assessment Tool [FRAX]) produced different estimates and to seek possible explanations for differences.

METHODS

We conducted a cross-sectional chart review at a tertiary osteoporosis centre (Dr. David Hanley Osteoporosis Centre in Calgary). Included patients were women referred for consideration of osteoporosis pharmacotherapy who attended a consultation between 2016 and 2019 and whose charts contained 10-year osteoporotic fracture risk estimates using both the CAROC tool (based on bone mineral density [BMD] results) and FRAX (based on BMD results and clinically assessed fracture risk factors). Risk estimates provided on BMD reports (calculated with CAROC) and generated through osteoporosis clinic consultation (calculated with FRAX, including BMD) were categorized as low (< 10.0%), moderate (10.0%-19.9%) or high (≥ 20.0%). Estimates were considered discordant when they placed the patient in different risk categories.

RESULTS

Of 190 patients evaluated, 99 (52.1%) had discordant risk estimates. Although a similar proportion were considered high risk by BMD reports using the CAROC tool (17.9%) and clinic charts using FRAX (19.5%), the 2 methods identified different patients as being high risk. Around the crucial high-risk (20.0%) treatment threshold, discordance was present in 37 patients (19.5%, 95% confidence interval [CI] 14.5%-25.7%); discordance around the moderate-risk (10.0%) threshold was present in 69 (36.3%, 95% CI 29.5%-43.2%) patients. Disagreement regarding fracture history between BMD reports and clinic charts was observed in 19.8% of patients.

INTERPRETATION

Fracture risk estimates on BMD reports (using the CAROC tool) and those calculated in the clinical setting (using FRAX) frequently result in different risk classification. Osteoporosis treatment decisions may differ in up to half of patients depending on which estimate is used, highlighting the need for a consistent and accurate assessment process for fracture risk.

Controversies Surrounding the BMD Reporting Standard for the Determination of 10-Year Absolute Fracture Risk: A Canadian Perspective

The Canadian Association of Radiologists and Osteoporosis Canada currently endorse a fracture risk prediction tool called CAROC. It has been used in Canada since 2005 with an update in 2010. It is an integral part of bone mineral densitometry reporting across the country. New osteoporosis guidelines from Osteoporosis Canada (OC) are expected in the near future. There has been pressure on radiologists to report fracture risk using an alternative fracture risk prediction platform called FRAX. In addition, OC collaborated in the development of the Canadian FRAX model and has been copromoting both FRAX and CAROC, raising the prospect that new guidelines may seek to replace CAROC with FRAX for fracture risk determination. A number of concerns have been raised about FRAX, including: (1) FRAX has not released its algorithms to the public domain with the consequence that it is impossible to verify results for an individual patient; (2) FRAX has incorrectly claimed that it was developed by the World Health Organization (WHO) and has used this affiliation to promote itself until recently ordered by the WHO to desist; (3) FRAX requires collection of additional clinical information beyond that needed for CAROC, and this patient-reported medical data is prone to substantial error; and (4) despite claims to the contrary, there are no valid studies comparing FRAX to CAROC. We believe it is important that radiologists be aware of these issues in order to provide input into future Technical Standards for Bone Mineral Densitometry Reporting of the Canadian Association of Radiologists.