Efficacy of switching from teriparatide to zoledronic acid or denosumab on bone mineral density and biochemical markers of bone turnover in older patients with severe osteoporosis: a real-life study

Purpose: Osteoporosis is characterized by loss of bone mass and susceptibility to fracture. Skeletal effects of teriparatide (TPT) are not persistent after drug withdrawal and sequential therapy with bisphosphonates or denosumab (Dmab) after TPT discontinuation represents a valid option. Here, the two sequential strategies were evaluated in severe osteoporotic patients. Methods: The study retrospectively enrolled 56 severe osteoporotic patients who received TPT for 24 months followed by 24 months of zoledronic acid (ZOL) (TPT + ZOL) or Dmab (TPT+Dmab). Clinical features, incident fractures, bone mineral density (BMD) measurements, and bone marker profiles were collected. One-way ANOVA analyzed the difference between mean T-scores at baseline, after 24 months of TPT, and after 2 doses of ZOL or after at least 3 doses of Dmab. Results: Twenty-three patients received TPT + ZOL (19 females, 4 males; median [IR] age, 74.3 [66.9, 78.6] years) and 33 patients received TPT+Dmab (31 females, 2 males; mean [IR] age, 66.6 ± 11.3 years). Mean lumbar and hip T-scores were increased after both TPT + ZOL and TPT+Dmab (all p < 0.05 vs baseline). The size effects induced by TPT + ZOL on the lumbar and hip BMD T-scores were similar to those observed with TPT+Dmab with mean T-scores increases of about 1 and 0.4 SD, respectively. No significant between-group differences were identified. Incident fragility fractures occurred in 3 (13%) patients treated with TPT + ZOL and in 5 (15%) patients treated with TPT+Dmab. Conclusions: Sequential TPT + ZOL therapy is likely to increase bone mineralization at the lumbar level and to stabilize it at the femoral level, similarly to what obtained with the sequential TPT+Dmab. Both ZOL and Dmab are suggested to be effective sequential treatments after TPT.