Bone Structural Parameters as Measured by 3-Dimensional Dual-Energy X-Ray Absorptiometry Are Superior in Black Women and Demonstrate Unique Associations With Prior Fracture Versus White Women.

OBJECTIVE

Black patients fracture less often than White patients at any given bone mineral density (BMD). This may be related to superior bone structure; however, bone structure is challenging to measure in clinical practice. Advances in 3-dimensional (3D) modeling have allowed for the measurement of trabecular and cortical parameters from dual-energy x-ray absorptiometry (DXA). This technology, known as 3D-DXA, may provide a way to assess hitherto unexplained differences in bone structure between Black and White patients.

METHODS

This is a secondary analysis of 775 women (368 Black and 407 White) previously recruited from an osteoporosis clinic. All women had undergone DXA and vertebral fracture assessment, and 3D-DXA was run retrospectively on the proximal femur BMD scan. Participants were classified as having a prior fracture if there was a fracture on vertebral fracture assessment or a self-reported history of fragility fracture.

RESULTS

Black women had generally superior 3D-DXA parameters, with the largest differences in cortical thickness of the femoral neck (FN) and buckling ratio of the FN. There were substantial differences in associations between fracture and 3D-DXA parameters in Black women compared with White women. After adjusting for age, glucocorticoids, and areal BMD T-score, cortical thickness of the FN was significantly associated with prior fracture (odds ratio, 1.4 per standard deviation decline; 95% CI, 1.0-1.9; P = .04) in Black women but not White women.

CONCLUSION

3D-DXA parameters were superior in Black women than in White women, and cortical thickness of the FN was associated with fractures only in Black women. 3D-DXA may improve fracture risk assessment in Black patients.