Relationship Between Bone Mineral Density T-Score and Nonvertebral Fracture Risk Over 10 Years of Denosumab Treatment

Although treat-to-target strategies are being discussed in osteoporosis, there is little evidence of what the target should be to reduce fracture risk maximally. We investigated the relationship between total hip BMD T-score and the incidence of nonvertebral fracture in women who received up to 10 years of continued denosumab therapy in the FREEDOM (3 years) study and its long-term Extension (up to 7 years) study. We report the percentages of women who achieved a range of T-scores at the total hip or femoral neck over 10 years of denosumab treatment (1343 women completed 10 years of treatment). The incidence of nonvertebral fractures was lower with higher total hip T-score. This relationship plateaued at a T-score between -2.0 and -1.5 and was independent of age and prevalent vertebral fractures, similar to observations in treatment-naïve subjects. Reaching a specific T-score during denosumab treatment was dependent on the baseline T-score, with higher T-scores at baseline more likely to result in higher T-scores at each time point during the study. Our findings highlight the importance of follow-up BMD measurements in patients receiving denosumab therapy because BMD remains a robust indicator of fracture risk. These data support the notion of a specific T-score threshold as a practical target for therapy in osteoporosis. © 2019 The Authors Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR)