Trabecular bone score improves fracture risk assessment in glucocorticoid-induced osteoporosis

Abstract

Objective: To analyse the clinical utility of trabecular bone score (TBS) evaluation for fracture risk assessment in glucocorticoid (GC)-treated patients compared with BMD assessment.

Methods: One hundred and twenty-seven patients on GC treatment were included [mean age 62 (18) years, 63% women] in this cross-sectional study. The medical history, anthropometric data, lumbar and femoral BMD (DXA) [considering osteoporosis (OP): T-score ⩽-2.5], TBS (considering degraded microarchitecture: <1.230) and dorsolumbar X-ray [to assess vertebral fractures (VF)] were evaluated. BMD and TBS sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were evaluated to determine the diagnostic accuracy of the two methods.

Results: All patients were receiving GC treatment for autoimmune diseases during 47.7 (68.9) months at a mean daily dose of 14.5 mg; 17% had VF, 28% any type of fragility fracture (VF + non-VF), 29% OP and 52% degraded microarchitecture. Degraded microarchitecture was significantly more frequent than densitometric OP in patients with VF (76% vs 38%) and with any fragility fracture (69% vs 36%). For VF, TBS and BMD sensitivity, specificity, PPV, and NPV were 0.76, 0.53, 0.25 and 0.92, and 0.38, 0.72, 0.22 and 0.85, respectively. Specificity increased to 0.89 for VF and 0.9 for any fragility fracture on combining BMD+TBS. TBS had better ability than BMD to discriminate between patients with fracture, especially VF (area under the curve = 0.73).

Conclusion: TBS seems to have greater discriminative power than BMD for fracture risk assessment in GC-treated patients, confirming the utility of this method as a complementary tool in the diagnosis of GC-induced OP.

Keywords: Glucocorticoid-induced osteoporosis; autoimmune diseases; bone microarchitecture; bone mineral density; discriminatory ability; fracture risk; trabecular bone score; vertebral fractures.