Switching to denosumab and teriparatide after long-term bisphosphonate use was associated with increased bone mineral density (BMD) at the spine, but the increases at the total hip and femoral neck were greater with denosumab, according to study results published in The Journal of Clinical Endocrinology & Metabolism.

There is only one head-to-head randomized controlled trial comparing denosumab and teriparatide treatment, in which approximately two-thirds of the patients had not received bisphosphonates. Researchers in this study used real-world data to compare changes in BMD after switching to teriparatide vs denosumab in patients with prior long-term bisphosphonate treatment.

The observational cohort study enrolled patients aged >45 years with osteoporosis treated in 2 academic medical centers in the United States. All patients were previously treated with bisphosphonate for ≥12 months before switching to denosumab or teriparatide. Patients were required to have received denosumab or teriparatide for ≥6 months and undergone ≥2 dual-energy x-ray absorptiometry scans.

The primary outcomes were the differences in annualized change in BMD between teriparatide and denosumab from baseline at the lumbar spine, total hip, and femoral neck.

The analysis included 215 eligible patients (94% women; mean age, 70±10 years). Prior bisphosphonate therapy was given for a median duration of 7.0 years. Of these participants, 105 patients were treated with denosumab and 110 received teriparatide.

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Treatment with denosumab was associated with a significant BMD increase in all 3 anatomic sites. However, teriparatide was associated with a greater annualized BMD increase at the lumbar spine by 1.3% (95% CI, 0.02%-2.7%; P =.046) compared with patients receiving denosumab.

On the other hand, teriparatide was also associated with greater annualized BMD loss at the total hip by -2.2% (95% CI, -2.9% to -1.5%; P <.001) and femoral neck by -1.1% (95% CI, -2.1% to -0.1%; P =.029) vs denosumab. Participants receiving teriparatide had BMD loss at the total hip and femoral neck in the first year, with no overall change over 2 years.

The study had several limitations, including the retrospective observational design and possible unmeasured confounders. Furthermore, various bisphosphonates were used in the period before switching to teriparatide or denosumab, with inherent differences in efficacy. Last, the researchers did not investigate differences in fracture risk given the low fracture incidence in the study population.

“[O]ur results suggest the decision of switching to teriparatide should be made with caution, especially for patients at high risk of hip fracture,” concluded the researchers.

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Reference

Lyu H, Zhao SS, Yoshida K, et al. Comparison of teriparatide and denosumab in patients switching from long-term bisphosphonate use [published online July 2, 2019]. J Clin Endocrinol Metab. doi:10.1210/jc.2019-00924