Real-life effects of pharmacological osteoporosis treatments on bone mineral density by quantitative computed tomography

Introduction: Monitoring of bone mineral density (BMD) is used to assess pharmacological osteoporosis therapy. This study examined the real-life effects of antiresorptive and osteoanabolic treatments on volumetric BMD (vBMD) of the spine by quantitative computed tomography (QCT).

Materials and methods: Patients aged ≥ 50 years with a vBMD < 120 mg/ml had ≥ 2 QCT. For analysis of therapy effects, the pharmacological treatment and the duration of each therapy were considered. Identical vertebrae were evaluated in all vBMD measurements for each patient. A linear mixed model with random intercepts was used to estimate the effects of pharmacological treatments on vBMD.

Results: A total of 1145 vBMD measurements from 402 patients were analyzed. Considering potential confounders such as sex, age, and prior treatment, a reduction in trabecular vBMD was estimated for oral bisphosphonates (- 1.01 mg/ml per year; p < 0.001), intravenous bisphosphonates (- 0.93 mg/ml per year; p = 0.015) and drug holiday (- 1.58 mg/ml per year; p < 0.001). Teriparatide was estimated to increase trabecular vBMD by 4.27 mg/ml per year (p = 0.018). Patients receiving denosumab showed a statistically non-significant decrease in trabecular vBMD (- 0.44 mg/ml per year; p = 0.099). Compared to non-treated patients, pharmacological therapy had positive effects on trabecular vBMD (1.35 mg/ml; p = 0.001, 1.43 mg/ml; p = 0.004, 1.91 mg/ml; p < 0.001, and 6.63 mg/ml; p < 0.001 per year for oral bisphosphonates, intravenous bisphosphonates, denosumab, and teriparatide, respectively).

Conclusion: An increase in trabecular vBMD by QCT was not detected with antiresorptive agents. Patients treated with teriparatide showed increasing trabecular vBMD. Non-treatment led to a larger decrease in trabecular vBMD than pharmacological therapy.