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.