Endocrine Abstracts

JOINT87

Introduction: Osteoporosis management is often tailored to the specific risk of the patient. Treatment classes include anti-resorptive medications versus anabolic agents. Theoretically, synergistic activity would provide greater efficacy than monotherapy, yet this has not been studied in detail.

Objectives: The purpose of this study is to assess the effectiveness of combination therapy with both bisphosphonates and teriparatide compared to sole therapy with bisphosphonates in relation to pathological fractures and bone mineral density.

Methods: A retrospective study was performed with TriNetX Global Collaborative Network, accessing de-identified data from 143 healthcare organizations. Cohorts A was defined based on the diagnosis of osteoporosis and receiving treatment with both a bisphosphonate and teriparatide (n = 16, 308), and cohort B was defined based on the presence of osteoporosis and receiving treatment with a bisphosphonate alone (n=548, 405). All genders were analyzed, and no age-limit was included. An observation period was defined as 1 day after the index event, ending 5 years after. Cohorts were balanced with propensity score matching, with n = 16, 754 per cohort. Cohorts were balanced for age at index, race, tobacco use, systemic corticosteroid therapy, body mass index, alcohol abuse, calcium and vitamin D supplementation, diagnosis of vitamin D deficiency, family history of osteoporosis, prior history of fractures, and baseline Z-score of the lumbar spine and hip. Key outcomes assessed included pathologic fractures at the hip, vertebrae and unspecified sites, and bone mineral density (Z-score) at both the hip and lumbar spine.

Results: The average age at index was 69.3 +/- 11.3 years, with 73.3% white and 85% female. Data demonstrated there was a greater risk for pathologic fracture (site unspecified) with combination therapy over monotherapy (Relative Risk 3.734, 95% CI: 2.821-4.944, P< 0.0001), as well as for collapsed vertebra (Relative Risk 1.816, 95% CI: 1.507-2.187, P< 0.0001). There was no significant difference in risk of pathologic fracture between the two cohorts (Relative Risk 1.285, 95% CI: 0.693-2.378, P = 0.4255), nor of the Z-score of the hip (P = 0.8839) and lumbar spine (P=0.3612).

Conclusion: This study demonstrates bisphosphonate monotherapy outperformed combination therapy (bisphosphonate and teriparatide) in reducing fracture risk, with no difference in bone mineral density enhancement. These findings suggest an antagonistic relationship (rather synergistic) in the presence of two differing therapeutic classes (anti-resorptive and anabolic). Further studies are needed to concur such findings.