High fracture probability with FRAX® usually indicates densitometric osteoporosis: implications for clinical practice

Abstract

Most patients designated as high risk of fracture using fracture risk assessment tool (FRAX) with femoral neck bone mineral density (BMD) (i.e., 10-year major osteoporotic fracture probability exceeding 20% or hip fracture exceeding 3%) have one or more T-scores in the osteoporotic range; conversely, almost no high risk patients have normal T-scores at all bone mineral density measurement sites. We determined the agreement between a FRAX designation of high risk of fracture [defined as 10-year major osteoporotic fracture probability (≥ 20%) or hip fracture probability (≥ 3%)] and the WHO categorizations of bone mineral density according to T-score. Ten-year FRAX probabilities calculated with femoral neck BMD were derived using both Canadian and US white tools for a large clinical cohort of 36,730 women and 2,873 men age 50 years and older from Manitoba, Canada. Individuals were classified according to FRAX fracture probability and BMD T-scores alone. Most individuals designated by FRAX as high risk of major osteoporotic fracture had a T-score in the osteoporotic range at one or more BMD measurement sites (85% with Canadian tool and 83% with US white tool). The majority of individuals deemed at high risk of hip fracture had one or more T-scores in the osteoporotic range (66% with Canadian tool and 64% with US white tool). Conversely, there were extremely few individuals (<1%) who were at high risk of major osteoporotic or hip fracture with normal T-scores at all BMD measurement sites. A FRAX designation of high risk of fracture is usually associated with a densitometric diagnosis of osteoporosis.