Areal and volumetric bone mineral density and risk of multiple types of fracture in older men

Although many studies have examined the association between low bone mineral density (BMD) and fracture risk in older men, none have simultaneously studied the relationship between multiple BMD sites and risk of different types of fractures. Using data from the Osteoporotic Fractures in Men study, we evaluated the association between areal BMD (aBMD) by dual-energy X-ray absorptiometry (DXA) and volumetric BMD (vBMD) by quantitative computed tomography (QCT) measurements, and different types of fractures during an average of 9.7 years of follow-up. Men answered questionnaires about fractures every 4 months (> 97% completions). Fractures were confirmed by centralized review of radiographic reports; pathological fractures were excluded. Risk of fractures was assessed at the hip, spine, wrist, shoulder, rib/chest/sternum, ankle/foot/toe, arm, hand/finger, leg, pelvis/coccyx, skull/face and any non-spine fracture. Age and race adjusted Cox proportional-hazards modeling was used to assess the risk of fracture in 3301 older men with both aBMD (at the femoral neck (FN) and lumbar spine) and vBMD (at the trabecular spine and FN, and cortical FN) measurements, with hazard ratios (HRs) expressed per standard deviation (SD) decrease. Lower FN and spine aBMD were associated with an increased risk of fracture at the hip, spine, wrist, shoulder, rib/chest/sternum, arm, and any non-spine fracture (statistically significant HRs per SD decrease ranged from 1.24-3.57). Lower trabecular spine and FN vBMD were associated with increased risk of most fractures with statistically significant HRs ranging between 1.27 and 3.69. There was a statistically significant association between FN cortical vBMD and fracture risk at the hip (HR = 1.55) and spine sites (HR = 1.26), but no association at other fracture sites. In summary, both lower aBMD and vBMD were associated with increased fracture risk. The stronger associations observed for trabecular vBMD than cortical vBMD may reflect the greater metabolic activity of the trabecular compartment.