The utility of absolute risk prediction using FRAX (R) and Garvan Fracture Risk Calculator in daily practice

Abstract

Objectives: There are two commonly used fracture risk prediction tools FRAX® and Garvan Fracture Risk Calculator (GARVAN-FRC). The objective of this study was to investigate the utility of these tools in daily practice. Study design: A prospective population-based 5-year follow-up study was conducted in ten general practice centres in the Netherlands. For the analyses, the FRAX® and GARVAN-FRC 10-year absolute risks (FRAX® does not have 5-year risk prediction) for all fractures were used. Results: Among 506 postmenopausal women aged ≥60 years (mean age: 67.8 ± 5.8 years), 48 (9.5%) sustained a fracture during follow-up. Both tools, using BMD values, distinguish between women who did and did not fracture (10.2% vs. 6.8%, respectively for FRAX® and 32.4% vs. 39.1%, respectively for GARVAN-FRC, p < 0.0001) at group level. However, only 8.9% of those who sustained a fracture had an estimated fracture risk ≥20% using FRAX® compared with 53.3% using GARVAN-FRC. Although both underestimated the observed fracture risk, the GARVAN-FRC performed significantly better for women who sustained a fracture (higher sensitivity) and FRAX® for women who did not sustain a fracture (higher specificity). Similar results were obtained using age related cut off points. Conclusions: The discriminant value of both models is at least as good as models used in other medical conditions; hence they can be used to communicate the fracture risk to patients. However, given differences in the estimated risks between FRAX® and GARVAN-FRC, the significance of the absolute risk must be related to country-specific recommended intervention thresholds to inform the patient.