A Meta-Analysis of Trabecular Bone Score in Fracture Risk Prediction and Its Relationship to FRAX

Abstract

Trabecular bone score (TBS) is a gray-level textural index of bone microarchitecture derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images. TBS is a bone mineral density (BMD)-independent predictor of fracture risk. The objective of this metaanalysis was to determine whether TBS predicted fracture risk independently of FRAX probability and to examine their combined performance by adjusting the FRAX probability for TBS. We utilized individual-level data from 17,809 men and women in 14 prospective population-based cohorts. Baseline evaluation included TBS and the FRAX risk variables, and outcomes during follow-up (mean 6.7 years) comprised major osteoporotic fractures. The association between TBS, FRAX probabilities, and the risk of fracture was examined using an extension of the Poisson regression model in each cohort and for each sex and expressed as the gradient of risk (GR; hazard ratio per 1 SD change in risk variable in direction of increased risk). FRAX probabilities were adjusted for TBS using an adjustment factor derived from an independent cohort (the Manitoba Bone Density Cohort). Overall, the GR of TBS for major osteoporotic fracture was 1.44 (95% confidence interval [CI] 1.35-1.53) when adjusted for age and time since baseline and was similar in men and women (p > 0.10). When additionally adjusted for FRAX 10-year probability of major osteoporotic fracture, TBS remained a significant, independent predictor for fracture (GR ¼ 1.32, 95% CI 1.24-1.41). The adjustment of FRAX probability for TBS resulted in a small increase in the GR (1.76, 95% CI 1.65-1.87 versus 1.70, 95% CI 1.60-1.81). A smaller change in GR for hip fracture was observed (FRAX hip fracture probability GR 2.25 vs. 2.22). TBS is a significant predictor of fracture risk independently of FRAX. The findings support the use of TBS as a potential adjustment for FRAX probability, though the impact of the adjustment remains to be determined in the context of clinical assessment guidelines.

Effect of denosumab on trabecular bone score in postmenopausal women with osteoporosis

“…The DXA scans of vertebrae L1-L4 obtained to assess lumbar spine BMD can also be used to generate TBS, thereby producing complementary skeletal information from the same examination [6]. TBS has been shown to be significantly associated with direct measurements of bone microarchitecture and mechanical behavior [5,[8][9][10] and is predictive of current [6,[11][12][13][14][15][16] and future [17][18][19] fragility fractures in postmenopausal women with primary osteoporosis [19,20]. TBS can also be used to assess fracture risk in patients with specific causes of secondary osteoporosis such as hyperparathyroidism, diabetes, and glucocorticoid treatment [21,22].…”

“…TBS can also be used to assess fracture risk in patients with specific causes of secondary osteoporosis such as hyperparathyroidism, diabetes, and glucocorticoid treatment [21,22]. TBS increases the ability of the Fracture Risk Assessment Tool (FRAX) to categorize fracture risk, and it has been incorporated into the FRAX model as an adjustment factor [20,23,24]. Thus, TBS has been newly included in international guidelines [25], providing an additional tool to identify and improve the characterization of patients at risk for fracture and in need of therapeutic intervention.…”

TBS and bone strength

“…A meta-analysis including 17 809 persons (both men and women) has been recently published by McCloskey et al 6 The gradient of risk (GR) of TBS for major osteoporotic fracture was 1.44 (95% CI: 1.35-1.53) when adjusted for age and time since baseline and was similar in men and women. The gradient was quite similar for hip fracture: 1.44 (95% confidence interval (CI): 1.28-1.62).…”

“…6 Also, the adjustment of FRAX probability for TBS resulted in no change in the GR (1.76, 95% CI: 1.65, 1.87 vs 1.70, 95% CI: 1.60-1.81), although some increase or decrease may be detected according to age. 6 Owing to these findings, it is now possible to include in the FRAX the value of TBS for improving the calculation of the probability of both major and hip fractures.…”

“…6 Also, the adjustment of FRAX probability for TBS resulted in no change in the GR (1.76, 95% CI: 1.65, 1.87 vs 1.70, 95% CI: 1.60-1.81), although some increase or decrease may be detected according to age. 6 Owing to these findings, it is now possible to include in the FRAX the value of TBS for improving the calculation of the probability of both major and hip fractures.What Evidence Do We Have Today That TBS Reflects Bone Microarchitecture?Because of its measurement conditions (images obtained from DXA), the TBS cannot be considered as a true parameter measuring bone microarchitecture. Several ex vivo studies investigated the relationship between TBS and microarchitectural parameters.…”