Samelson EJ, et al. - In a large international cohort of 7,254 individuals (66% women and 34% men) with mean baseline age 69 years (SD 9, range 40–96), researchers investigated if indices of high-resolution peripheral quantitative CT (HR-pQCT) were associated with fracture risk independently of femoral neck areal bone mineral density (aBMD) and the Fracture Risk Assessment Tool (FRAX) score. They found HR-pQCT indices and failure load were useful for allowing a better prediction of fracture beyond femoral neck aBMD or FRAX scores alone. Findings were suggestive of an independent contribution of deficits in trabecular and cortical bone density and structure to fracture risk, supporting previous reports. The highest risk population might be more readily detected taking into account these measurements and morphological assessment of the peripheral skeleton.

Methods

• Participants in 8 cohorts from the USA (Framingham, Mayo Clinic), France (QUALYOR, STRAMBO, OFELY), Switzerland (GERICO), Canada (CaMos), and Sweden (MrOS) were evaluated.
• Researchers used Cox proportional hazard ratios (HRs) to determine the link between HR-pQCT bone indices (per 1 SD of deficit) and incident fracture, adjusting for age, sex, height, weight, and cohort, and then additionally for femoral neck DXA aBMD or FRAX.

Results

• With mean baseline age 69 years (SD 9, range 40–96), 7,254 individuals (66% women and 34% men) were assessed.
• Incident fractures were seen in 765 (11%) participants during a mean follow-up of 4·63 years (SD 2·41) years, of these subjects, 633 (86%) had femoral neck T scores greater than −2·5.
• Findings revealed that after adjustment for age, sex, cohort, height, and weight, peripheral skeleton failure load showed the greatest relation to risk of fracture: tibia HR 2·40 (95% CI 1·98–2·91) and radius 2·13 (1·77–2·56) per 1 SD decrease.
• With regard to HRs for other bone indices, the range was from 1·12 (95% CI 1·03–1·23) per 1 SD increase in tibia cortical porosity to 1·58 (1·45–1·72) per 1 SD decrease in radius trabecular volumetric bone density.
• Attenuation was noted in the associations after further adjustment for femoral neck aBMD or FRAX score but these associations continued to be significant for most bone parameters.
• The fracture was best predicted by a model including cortical volumetric bone density, trabecular number, and trabecular thickness at the distal radius and a model including these indices plus cortical area at the tibia.