Efficacy Comparison of 6-Month Romosozumab Plus Denosumab Versus 12-Month Romosozumab in Koreans

Abstract Objective Romosozumab (Romo) rapidly increases bone mineral density (BMD), with approximately 70% of gains occurring within the first 6 months. The present study aimed to compare the efficacy of 6-month Romo followed by denosumab (Romo6M+Dmab) versus 12-month Romo (Romo12M) in osteoporosis treatment. Methods In this multicenter retrospective study, 156 treatment-naïve patients (Romo6M+Dmab: n=41; Romo12M: n=115) were included. BMD at lumbar spine (LS-BMD), total hip (TH-BMD), and femoral neck (FN-BMD), trabecular bone score (TBS), and bone turnover markers (BTMs) were assessed at 12 months. In a subset of 96 patients (Romo6M+Dmab: n=27; Romo12M: n=69), BMD was reassessed at 24 months after 12 months of additional Dmab. Analysis used a mixed-effects model for repeated measures, adjusting for baseline and visit. Results At 12 months, least-squares mean (standard error, SE) percent changes in LS-BMD were 16.9% (4.6%) for Romo6M+Dmab and 16.9% (3.4%) for Romo12M. TH-BMD increased by 4.6% (3.9%) and 4.4% (2.9%), FN-BMD by 3.2% (3.9%) and 4.2% (3.1%), respectively. No significant treatment-by-time differences in LS-BMD (p=.936), TH-BMD (p=.911), or FN-BMD (p=.357) were detected. Baseline, 1-month, and 6-month BTM levels were comparable between groups; at 12 months, BTMs were higher in Romo12M (p<.001). TBS increased significantly only in Romo12M, although the between-group difference was not statistically significant (p=.989). BMD gains at 24 months remained similar. Conclusions Sequential Romo6M+Dmab treatment demonstrates comparable efficacy to Romo12M treatment in improving BMD, with fewer injections and potential cost benefits.