Relationship between bone mineral density changes with denosumab treatment and risk reduction for vertebral and nonvertebral fractures

✍ Scribed by Matthew Austin; Yu-Ching Yang; Eric Vittinghoff; Silvano Adami; Steven Boonen; Douglas C Bauer; Gerolamo Bianchi; Michael A Bolognese; Claus Christiansen; Richard Eastell; Andreas Grauer; Federico Hawkins; David L Kendler; Beatriz Oliveri; Michael R McClung; Ian R Reid; Ethel S Siris; Jose Zanchetta; Cristiano AF Zerbini; Cesar Libanati; Steven R Cummings; for the FREEDOM Trial

• Publisher: American Society for Bone and Mineral Research
• Year: 2012
• Tongue: English
• Weight: 96 KB
• Volume: 27
• Category: Article
• ISSN: 0884-0431
• DOI: 10.1002/jbmr.1472

✦ Synopsis

Dual-energy X-ray absorptiometric bone mineral density (DXA BMD) is a strong predictor of fracture risk in untreated patients. However, previous patient-level studies suggest that BMD changes explain little of the fracture risk reduction observed with osteoporosis treatment. We investigated the relevance of DXA BMD changes as a predictor for fracture risk reduction using data from the FREEDOM trial, which randomly assigned placebo or denosumab 60 mg every 6 months to 7808 women aged 60 to 90 years with a spine or total hip BMD T-score < −2.5 and not < −4.0. We took a standard approach to estimate the percent of treatment effect explained using percent changes in BMD at a single visit (months 12, 24, or 36). We also applied a novel approach using estimated percent changes in BMD from baseline at the time of fracture occurrence (time-dependent models). Denosumab significantly increased total hip BMD by 3.2%, 4.4%, and 5.0% at 12, 24, and 36 months, respectively. Denosumab decreased the risk of new vertebral fractures by 68% (p < 0.0001) and nonvertebral fracture by 20% (p = 0.01) over 36 months. Regardless of the method used, the change in total hip BMD explained a considerable proportion of the effect of denosumab in reducing new or worsening vertebral fracture risk (35% [95% confidence interval (CI): 20%–61%] and 51% [95% CI: 39%–66%] accounted for by percent change at month 36 and change in time-dependent BMD, respectively) and explained a considerable amount of the reduction in nonvertebral fracture risk (87% [95% CI: 35% – >100%] and 72% [95% CI: 24% – >100%], respectively). Previous patient-level studies may have underestimated the strength of the relationship between BMD change and the effect of treatment on fracture risk or this relationship may be unique to denosumab. © 2012 American Society for Bone and Mineral Research