Bone mineral density (BMD) and vertebral trabecular bone score (TBS) for the identification of elderly women at high risk for fracture: the SEMOF cohort study

Abstract

Purpose: To determine the predictive value of the vertebral trabecular bone score (TBS) alone or in addition to bone mineral density (BMD) with regard to fracture risk.

Methods: Retrospective analysis of the relative contribution of BMD [measured at the femoral neck (FN), total hip (TH), and lumbar spine (LS)] and TBS with regard to the risk of incident clinical fractures in a representative cohort of elderly post-menopausal women previously participating in the Swiss Evaluation of the Methods of Measurement of Osteoporotic Fracture Risk study.

Results: Complete datasets were available for 556 of 701 women (79 %). Mean age 76.1 years, LS BMD 0.863 g/cm², and TBS 1.195. LS BMD and LS TBS were moderately correlated (r ² = 0.25). After a mean of 2.7 ± 0.8 years of follow-up, the incidence of fragility fractures was 9.4 %. Age- and BMI-adjusted hazard ratios per standard deviation decrease (95 % confidence intervals) were 1.58 (1.16-2.16), 1.77 (1.31-2.39), and 1.59 (1.21-2.09) for LS, FN, and TH BMD, respectively, and 2.01 (1.54-2.63) for TBS. Whereas 58 and 60 % of fragility fractures occurred in women with BMD T score ≤-2.5 and a TBS <1.150, respectively, combining these two thresholds identified 77 % of all women with an osteoporotic fracture.

Conclusions: Lumbar spine TBS alone or in combination with BMD predicted incident clinical fracture risk in a representative population-based sample of elderly post-menopausal women.

Keywords: Bone mineral density; Fracture risk; Osteoporosis; Trabecular bone score.