FRAX without Bone Mineral Density Versus Osteoporosis Self‐Assessment Screening Tool as Predictors of Osteoporosis in Primary Screening of Individuals Aged 70 and Older

OBJECTIVES: To compare two well-validated tools--the FRAX without bone mineral density (BMD) and the Osteoporosis Self-Assessment Screening Tool (OST)--in predicting osteoporosis and to define thresholds above and below which it would be reasonable to recommend omitting BMD testing. DESIGN: Retrospective review. SETTING: General practices in Western Australia. PARTICIPANTS: Individuals aged 70 and older responding to a prospective audit of osteoporosis investigation and management for whom dual-energy X-ray absorptiometry scan results and clinical risk factor data were available (N = 626). MEASUREMENTS: Receiver operating characteristic (ROC) curves were compared, upper and lower thresholds for omission of screening BMD were proposed, and the statistical performance measures for the tests are reported. RESULTS: The areas under the ROC curves for the OST (0.76-0.82) were slightly better than for FRAX without BMD 10-year major osteoporotic fracture risk (0.64-0.76) in predicting osteoporosis at the defined sites. At defined lower thresholds, the tests were comparable in identifying a group with low osteoporosis risk (sensitivity 89.6-92.2%, specificity 35.0-39.9%), translating into 33.5% to 36.1% of tests saved at a cost of missing 7.8% to 10.4% of individuals with osteoporosis on BMD criteria. It was not possible to identify a useful upper threshold. CONCLUSION: At the defined thresholds, the OST is as good as FRAX without BMD in identifying a low-risk population subgroup for whom screening BMD can reasonably be omitted. This could reduce costs and improve access to treatment.