Lumbar spine trabecular bone score (TBS), a grey-level texture measure derived from spine dual-energy x-ray absorptiometry (DXA) images, is a BMD-independent risk factor for fracture (1). The use of TBS for guiding patient management is supported by guidelines from several organizations (2, 3, 4).

An unresolved and controversial question is whether there are ethnic differences that affect the use of TBS for fracture risk assessment. An international individual-level meta-analysis of observational cohort studies, included cohorts from Europe, North America and Asia, confirmed the ability of TBS to predict incident fractures in both women and men independent of fracture probability estimated with the FRAX tool (5). Indeed, despite ethnic diversity among populations included in the studies, there was low heterogeneity for the relationship between TBS and major osteoporotic fracture (I²= 31%) and hip fracture (I²= 5%). However, no population that identified as Black (term used in preference to African-American) was included. Subsequent data have suggested that TBS may show lower fracture discrimination in Black than White populations, and in one American university hospital report TBS was lower in Black than White individuals even after adjustment for age and tissue thickness (6, 7). Moreover, there are technical factors in TBS measurement that can potentially impact results. Notably, increasing abdominal soft tissue may create image noise and must be distinguished from degraded bone texture (8, 9). The current TBS algorithm uses body mass index (BMI) to adjust for this effect (10). However, a BMI-based adjustment may not fully capture differences in body composition and/or morphometry, and a tissue thickness adjusted TBS algorithm is in development.

The current analysis was undertaken to further explore whether self-identified ethnicity (White, Asian, Black) in women sent for DXA testing in routine clinical practice affects fracture risk stratification from TBS using a large clinical registry that includes all DXA tests for the Province of Manitoba, Canada.