In the Active-Controlled Fracture Study in Postmenopausal Women With Osteoporosis at High Risk (ARCH) clinical trial (NCT01631214), 1 year of romosozumab followed by alendronate reduced the risk of vertebral and nonvertebral fractures compared to alendronate alone in women with prevalent fracture. We performed post hoc analyses of data from patients in ARCH (romosozumab, n = 1739; alendronate, n = 1726) who had a baseline BMD measurement and received at least one open-label alendronate dose. We evaluated 1-year mean BMD and corresponding T-score changes; proportions of patients achieving T-scores > -2.5 at the total hip (TH), femoral neck (FN), and lumbar spine (LS); and group differences in fracture rates after 12 months, while all participants were on alendronate.[...]