Long-term impact of teriparatide on bone mineral density, trabecular bone score, and fracture risk relative to total hip T-score: A two-decade, registry-based cohort study.

Background Teriparatide followed by antiresorptive therapy exhibits fracture reduction efficacy for up to 2 years, but it remains unclear if this leads to sustained increases in bone mineral density (BMD) and trabecular bone score (TBS), and if BMD correlates with fracture risk reduction. Methods In this multicenter cohort study, the effect of teriparatide administration for 18-24 months, followed by antiresorptive therapy, was assessed in patients partipicipating in a nationwide Swiss osteoporosis registry. BMD and TBS were measured up to 10 years before and after teriparatide initiation. Results A total of 624 patients (87 % female, age 67 ± 13 years) were enrolled from May 2004 to December 2023. Among them, 198 (32 %) received no treatment prior to teriparatide, while 426 had received previous antiresorptive therapies (median duration 5.9 years [2.2, 8.0]). All patients underwent subsequent antiresorptive therapy, mainly with bisphosphonates and denosumab. The incidences of vertebral, hip, and any fractures were 0.96, 0.11, and 1.37, respectively, within 2 years prior to teriparatide initiation. The total hip T-score did not correlate with fracture reduction under teriparatide. After transitioning from teriparatide to an antiresorptive regimen, fracture incidence remained low and BMD was significantly higher for up to 5 years after teriparatide compared to the pre-treatment period (T-score + 0.876 for lumbar spine, p < 0.001; and + 0.112 for total hip, p < 0.005), while TBS increased by 0.047 (p < 0.001). Overall, significant improvement was observed in pretreated and treatment-naïve patients undergoing teriparatide treatment. Conclusion Teriparatide led to sustained lower incidences of vertebral, hip, and other fractures for up to 8 years after switching to antiresorptive agents in both pretreated and treatment-naïve patients. Additionally, BMD and TBS levels were significantly higher than those before teriparatide treatment. During teriparatide treatment, the total hip T-score did not correlate with fracture risk.