Lay summary
Fractures are an important health issue, occurring in >50% of older women. Although low bone density is a strong risk factor for fracture, 80% of fractures occur in women without low bone density. We are two-thirds of the way through a 10 year clinical trial in 1054 women investigating whether zoledronate, an effective treatment for osteoporosis, prevents bone loss and spinal fractures in early post-menopausal women with normal or only mildly low bone density when given very infrequently. The first participants completed 7 years of follow-up in June 2019. During the trial, zoledronate or an inactive agent (placebo) is administered every 5 years. The main outcomes are occurrence of new spinal fractures and changes in bone density. If the treatment is effective, the study will offer a more convenient approach to preventing fractures, potentially preventing a much higher proportion of fractures than with current strategies.