Teriparatide is an anabolic therapy used to treat patients with osteoporosis and is only approved for 2 years of treatment. This is the first study to look at two common osteoporosis drugs in maintaining its beneficial effects: denosumab and zoledronic acid. Denosumab treatment was associated with the greatest increase in bone mineral density (BMD) at the femoral neck and lumbar spine, an amount that was statistically greater than no treatment and zoledronic acid treatment.

BACKGROUND

Teriparatide, a hallmark treatment for osteoporosis, has been shown to increase BMD and bone turnover. This can be measured using BMD scans, N-terminal propeptide of type-1 collagen (P1NP) for bone formation and C-terminal telopeptide (CTX) for bone resorption. This study examines the effects of the two most common antiresorptive drugs prescribed following 2 years of teriparatide treatment: zoledronic acid and denosumab. The purpose of this study is to quantify the beneficial effects of teriparatide and compare the ability of each antiresorptive drug to maintain the effects.

METHODS

Ninety-four patients with prior fragility fractures were identified from a bone health clinic associated with a level I trauma center. All of the study participants completed 2 years of treatment with teriparatide between 2008 and 2013 followed by 2 years of treatment with zoledronic acid, denosumab, or no treatment. After excluding patients with insufficient laboratory data, 64 patients remained for analysis in this retrospective cohort study. Bone mineral density was measured in the lumbar spine and femoral neck.

RESULTS

Following completion of teriparatide, patients who were started on denosumab showed the largest increase in bone mineral density after 2 years of treatment: lumbar spine 4.94% ± 8.2%, femoral neck 5.68% ± 6.7%.

CONCLUSIONS

Patients who elected to discontinue osteoporosis treatment experienced a significant decline in the change in BMD compared to the change on teriparatide putting them at higher risk for recurrence of fragility fractures. Patients on denosumab following teriparatide had the largest increase in BMD.