Fracture risk gradient assessed by categories of bone mineral density and trabecular bone score: the Manitoba BMD Registry

Summary Trabecular bonescore (TBS) helps to predict fracture risk in older adults. In this registry-based cohort study of patients aged 40 years and older, reduction in bone mineral density (BMD) and TBS are complementary for fracture risk prediction enhancement with lower BMD imparting greater risk than reduction in TBS. Purpose Trabecular bone score (TBS) enhances fracture risk prediction independent of bone mineral density (BMD) in older adults. The purpose of this study was to further evaluate the gradient of fracture risk based on TBS tertile categories and WHO BMD categories, adjusted for other risk factors. Methods Using the Manitoba DXA registry, patients aged 40 years and older with spine/hip DXA and L1-L4 TBS were identified. Any incident fractures, major osteoporotic fractures (MOF), and hip fractures were identified. Cox regression models were used to estimate unadjusted and covariate-adjusted hazard ratios (HR, 95%CI) for incident fracture by BMD and TBS category and for each SD decrease in BMD and TBS. Results The study population included 73,108 individuals, 90% female with mean age 64 years. Mean (SD) minimum T-score was − 1.8 (1.1), and mean L1-L4 TBS was 1.257 (0.123). Lower BMD and TBS, both per SD, by WHO BMD category and by TBS tertile category, were significantly associated with MOF, hip, and any fracture (all HRs p < 0.001). However, the quantum of risk was consistently greater for BMD than TBS, with HRs showing non-overlapping CIs. Conclusion TBS is complementary to BMD in prediction of incident major, hip, and any osteoporosis-related fracture, but reductions in BMD impart greater risk than reductions in TBS on both continuous and categorical scales.