Bone Abstracts

Introduction: The purpose of this study was to quantify fracture risk associated with areal bone mineral density (BMD) in older men.

Methods: In this prospective analysis we followed 620 men aged 60–93 years (median 74.3 years) for a median 6.4 years, after baseline BMD assessments (performed 2001–2006) as part of the Geelong Osteoporosis Study. Based on WHO criteria, 33.5% had normal BMD at the femoral neck, 57.6% were osteopenic and 8.9% osteoporotic. Participants were followed until the end of 2010, or until sustaining a fracture, death, or emigration. Post-baseline fractures were ascertained radiologically.

Results: During the study 130 men died, 16 left the region, 63 sustained at least one fracture and 411 remained fracture-free, generating 3592 person years of follow-up. Most (86.5%) of the fractures occurred in men without osteoporosis on BMD criteria (17.9% with normal BMD, 68.7% with osteopenia) whereas 3.5% of the fractures occurred in men with osteoporosis. Age-standardised 5-year fracture risk was 2.94% (95%CI 1.20, 6.45) for normal BMD, 6.98% (95%CI 4.27, 11.11) for osteopenia and 17.71% (95%CI 6.62, 68.37) for osteoporosis. Using an age-adjusted Cox proportional hazards model and normal BMD as the referent group, the hazard ratio (HR) for fracture was 2.05 (95%CI 0.94, 4.45) and 4.47 (95%CI 1.54, 13.02) for men of median age with osteopenia and osteoporosis, respectively. The relative risk of those with osteoporosis as compared to those with osteopenia was 2.18 (95%CI 0.92, 5.17). Prior low trauma fracture was significant in the models, with HR 1.85 (95%CI 1.08, 3.15).

Conclusion: The categories of decreasing BMD defined increasing risk of fracture, with advancing age amplifying this risk. Although men with osteoporotic BMD were at greatest risk, they contributed 3.5% to the total burden of fractures. Two-thirds of the fractures arose from men with osteopenic BMD, who represented approximately half of the population at risk.