The effects of a FRAX revision for the USA

A revision (version 3.0) of the fracture risk assessment tool (FRAX) is developed based on an update of epidemiological information for the USA. With the revised tool, there were strong correlations (r > 0.99) between versions 2.0 and 3.0 for FRAX estimates of fracture probability, but the revised models gave lower probability estimates.

The aim of this study was to determine the effects of a revision of the epidemiological data used to compute fracture probabilities in the USA with FRAX.

Models were constructed to compute fracture probabilities based on updated fracture incidence and mortality rates in the USA. The models comprised the ten-year probability of hip fracture and the ten-year probability of a major osteoporotic fracture, both including femoral neck bone mineral density (BMD). For each model, fracture and death hazards were computed as continuous functions. The effect of the revised rates on fracture probability was examined by piecewise linear regression using multiple combinations of clinical risk factors and BMD.

At all ages, there was a strong correlation (r > 0.99) between version 2.0 and revised FRAX estimates of fracture probability. For a major osteoporotic fracture, the revised model gave lower median probabilities by 13% to 24% in men, depending on age, and by 19% to 24% in women. For hip fracture probability, the revised model gave lower median fracture probabilities by 40% and 27% at the ages of 50 and 60 years in men and by 43% and 30%, respectively, in women. At the ages of 70 years and older the revised model gave similar hip fracture probabilities as version 2.0 in both men and women.

The revised FRAX model for the USA (version 3.0) does not alter the ranking of fracture probabilities but provides lower probability estimates than version 2.0, particularly, in younger women and men.