The added value of trabecular bone score to FRAX® to predict major osteoporotic fractures for clinical use in Chinese older people: the Mr. OS and Ms. OS cohort study in Hong Kong

Abstract

The association of trabecular bone score (TBS) with fracture risk and its added predictive value to FRAX® for clinical use have never been independently evaluated in a Chinese population. TBS may improve the predictive power of FRAX® for clinical use in older Chinese men.

Introduction: Trabecular bone score (TBS) of lumbar spine on Dual X-ray densitometry provides information on bone architecture. We therefore examined the additive value of TBS to FRAX® in predicting major osteoporotic fractures (MOFs) in older Chinese people.

Methods: Four thousand community-dwelling Chinese men and women aged ≥65 years were followed up for fracture incidence for an average period of 9.94 and 8.82 years, respectively. At baseline, areal BMD of hip and lumbar spine were measured by DXA, TBS was estimated for the lumbar spine, and FRAX® for 10-year risk of MOFs (hip, clinical spine, shoulder, and wrist) was estimated. Cox regression model was used to evaluate the associations between TBS and FRAX® with the MOFs risk. The area under receiver-operating characteristic curve (AUC), integrated discrimination improvement (IDI), and category-based net reclassification improvement (NRI) were applied to evaluate the improved prediction ability.

Results: During the follow-up, 126 men and 215 women had at least one incident MOF. Each SD decrease in TBS was significantly associated with incident MOFs, with HR (95%CI) of 1.53 (1.30-1.80) and 1.40 (1.22-1.61) in men and women, respectively. TBS-adjusted FRAX® predicts better than FRAX® with a significantly increased AUC and IDI in men. Using specific intervention thresholds, TBS-adjusted FRAX® brings about 5 % overall correct reclassification for MOFs prediction than FRAX® in men. The increased correct MOFs risk classifications were not significant in older women.

Conclusions: TBS-adjusted FRAX® may improve the predictive power of FRAX® on MOFs for clinical use in older Chinese men.

Keywords: FRAX®; Major osteoporotic fractures; Prediction model; Trabecular bone score.