Introduction: Osteoporosis is defined as a bone mineral density (BMD) T-score of ≤ − 2.5 at either lumbar spine or femur. BMD T-score discordance between the lumbar spine and femur is classified as major or minor. Major discordance indicates osteoporosis at one site and normal BMD at another, while minor discordance indicates osteopenia at one site and normal or osteoporotic BMD at another. The purpose of this study was to investigate the rate of spine-hip BMD discordance in patients with osteoporotic vertebral compression fractures (OVCF), and the effect of BMD discordance on the treatment of osteoporosis.
Methods: We collected data on patients with osteoporotic vertebral fractures from the Catholic Medical Center Clinical Data Warehouse from January 2020 to December 2021. Each patient was categorized into two groups: concordance and discordance group. The discordance group was divided into two groups: minor discordance and major discordance group. We compared the degree of BMD improvement between the concordance and discordance groups. The therapeutic efficacy of two osteoporosis medications (ibandronate and denosumab) in each group was also evaluated.
Results: Among 2352 patients with OVCF, 260 patients met the inclusion criteria. Among them, 145 patients had BMD results at 1-year follow-up. The rate of concordance and discordance in patients with OVCF was 48.2% and 51.8%, respectively. Among the discordance rates, the major discordance rate was 10.3% and the minor discordance rate was 41.5%. After one year of osteoporosis treatment, lumbar spine and femur BMD increased significantly in the concordance group (p=0.000 and p=0.007, respectively). Only lumbar spine BMD increased (p=0.000) and femur BMD did not increase in the discordance group (p=0.619). There was no significant difference in the lumbar and femur BMD improvement between the concordance and discordance groups (0.051 vs 0.045, p=0.496; 0.027 vs 0.001, p=0.120). There was no significant difference between the concordance and discordance group in the improvement of BMD according to two osteoporosis medications (ibandronate, 0.025 vs 0.035, p=0.337; denosumab, 0.063 vs 0.050, p=0.269). In the concordance group, there was no difference in the degree of improvement of femur BMD by ibandronate and denosumab (0.011 vs 0.035, p=0.513), but lumbar spine BMD improved significantly more in denosumab than in ibandronate (0.025 vs 0.063, p=0.001). However, in the discordance group, there was no difference in the improvement of BMD according to the two medications (p=0.293 and p=0.230, respectively). In the discordance group, the degree of improvement of BMD was significantly higher in the lumbar osteoporosis group than in the femur osteoporosis group. (0.057 vs 0.025, p=0.012).
Conclusion: In patients with OVCF, the rate of BMD discordance was 51.8%. After one year of osteoporosis treatment, there was no significant difference in the BMD improvement between the concordance and discordance groups. Denosumab increased lumbar spine BMD more than ibandronate in the concordance group. In the discordance group, the degree of BMD improvement was significantly higher in the lumbar osteoporosis group than in the femur osteoporosis group. The study demonstrates the need for tailored treatment strategies in osteoporosis management for patients with BMD discordance.