Romosozumab FRAME Study: A Post Hoc Analysis of the Role of Regional Background Fracture Risk on Nonvertebral Fracture Outcome

In the pivotal Fracture Study in Postmenopausal Women with Osteoporosis (FRAME; NCT01575834), 1 year of the bone-forming agent romosozumab significantly reduced new vertebral and clinical fracture risk versus placebo. Nonvertebral fracture risk was not significantly reduced in the overall population, influenced by a low placebo-group fracture rate, observed particularly in the highest-enrolling region of Latin America. In year 1 of FRAME, postmenopausal women with a T-score of -2.5 to -3.5 at the total hip or femoral neck were randomized to subcutaneous romosozumab 210 mg or placebo once monthly for 12 months. Of 7180 randomized women, 43% were from Latin America, largely Colombia and Brazil. Prespecified analyses assessed fracture risk reductions by geographic regions. A significant treatment-by-geographic region interaction for the clinical (p = 0.029) and nonvertebral fracture (p = 0.042) endpoints led to further characterization of the Latin American population and comparison with the remaining study population, grouped post hoc as rest-of-world. Nonvertebral fracture efficacy in the overall population was also assessed by baseline fracture risk using the Fracture Risk Assessment Tool (FRAX). Romosozumab significantly and consistently reduced new vertebral fracture risk in Latin America (70% reduction; p = 0.014) and rest-of-world (74% reduction; p < 0.001). For nonvertebral fracture, risk reductions were observed in rest-of-world (42% reduction; p = 0.012), with no treatment effect observed in Latin America, where background nonvertebral fracture risk was low (1.2% in the placebo group). Consistent with this finding, in the overall population, greater reductions in nonvertebral fracture risk were observed among women with higher FRAX scores. These findings suggest that fracture risk assessment should consider regional factors in addition to classical risk factors, such as bone mineral density. In women at high risk for fracture, romosozumab reduced nonvertebral fracture risk within 1 year. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc.