Fracture burden in relation to low bone mineral density and FRAX(®) probability

Although the risk of fracture increases exponentially with declining bone mineral density, most fragility fractures have been shown to occur in individuals who do not meet the conventional densitometric definition for osteoporosis. The World Health Organization fracture risk assessment tool (FRAX(®)) estimates individual 10-yr major osteoporotic and hip fracture probabilities. Intervention criteria based on risk assessment have been proposed by several groups, including the National Osteoporosis Foundation (NOF). We determined the relationship between 10-yr fracture probability and subsequent fracture burden in 36,730 women and 2873 men aged 50yr and older. Using a major fracture probability cutoff of 20%, 29.4% of major osteoporotic fractures were identified in women and 4.9% in men. Based on a hip fracture probability cutoff of 3%, 54.1% of major osteoporotic fractures were detected in women and 53.4% in men. Using all NOF criteria, 65.9% of major osteoporotic fractures were detected in women and 69.3% in men. We conclude that men and women with FRAX probabilities below the high-risk NOF cutoffs have a high burden of major osteoporotic fractures. Strategies to enhance risk stratification in this group should be developed through international collaborations.