The Effects of Switch Therapy in Osteoporosis Treatment after Romosozumab after Comparing with Prior Treatment

Rationale. Although romosozumab is one of the most effective treatments for osteoporosis by increasing bone mineral density in the lumbar spine and femur and recommended for denosumab as switch therapy, these effects regarding its prior treatment have not yet been evaluated clearly. This study focused on the effects of switch therapy from romosozumab to denosumab in regard to prior treatment of osteoporosis including bone mineral density and bone turnover marker and other related factors. Patient Concerns. 15 osteoporotic patients were assigned to the naïve group, 15 were assigned to the teriparatide group, and 10 were assigned to the bisphosphonate group. Interventions. Patients who were treated as outpatients for osteoporosis with romosozumab for 1 year and switched to denosumab between 2020 and 2022 at our hospital were examined. Our hospital registry included 40 osteoporotic patients who were over 65 years of age with bone mineral density (bone mineral density): T score <−2.5 standard deviations (SDs) and fracture assessment tool (FRAX) score >20%. Outcomes. The naïve group had the highest increase in LS BMD among these three groups during switch therapy from romosozumab to denosumab, while there were no significant differences about adverse drug events and serum Ca concentration among them. There was no incidence of fracture. Conclusion. These findings indicate that the effects of osteoporotic treatment of switch therapy from romosozumab to denosumab were likely to affect prior treatment of osteoporosis.