Clinical Benefits of Denosumab vs Zoledronate in Postmenopausal Women Previously Treated with Alendronate: A Two-Year Retrospective Study.

Purpose: Due to various clinical considerations, postmenopausal osteoporosis patients initially treated with oral alendronate (ALN) therapy can later transition to either Denosumab (Dmab) or Zoledronate (ZOL). Using a two-year retrospective cohort, this study sought to thoroughly assess and contrast the frequency of osteoporotic fractures and fluctuations in bone mineral density (BMD) among patients switching from ALN therapy to either Dmab or ZOL. Patients and Methods: This retrospective cohort study enrolled 294 postmenopausal osteoporosis patients who transitioned from oral ALN to either Dmab or ZOL. The primary endpoint was new-onset osteoporotic fractures within 24 months, confirmed via clinical records and imaging (X-ray/CT/MRI). Secondary endpoint included annual percentage changes in BMD at the lumbar spine, total hip, and femoral neck. Results: There were no discernible variations between the Dmab and ZOL groups in terms of baseline BMD or prior fracture history. The median age of the Dmab group was higher than that of the ZOL group. In comparison to the ZOL group, the overall incidence of new-onset fractures was significantly lower in the Dmab group (3.79% vs 10.39%, raw p value = 0.028; FDR-adjusted p value = 0.028), especially for vertebral fractures (1.52% vs 8.44%, raw p value = 0.023; FDR-adjusted p value = 0.028). Furthermore, although BMD increased from baseline in both groups, the Dmab group improved much more than the ZOL group. Conclusion: In postmenopausal osteoporosis patients transitioning from oral ALN to other antiresorptive therapies, Dmab is demonstrated superior efficacy over ZOL in lowering risk of new-onset vertebral and overall fractures and sustaining BMD improvements over 24 months. These findings suggest that Dmab may represent a preferential strategy for optimizing clinical outcomes in sequential anti-osteoporosis treatment protocols.