Endocrine Abstracts

Introduction

Denosumab (Dab) withdrawal is associated with a quick loss in bone mineral density (BMD) and a high risk of multiple vertebral fractures. It is still not stablished which strategy best prevents BMD loss after Dab discontinuation.

Aim

Compare the use of bisphosphonates for one year after Dab withdrawal versus a tapering Dab regimen in terms of BMD and fracture occurrence.

Methods

Descriptive retrospective study including 20 patients with osteoporosis treated with Dab, whose treatment was retired after achieving their BMD target (T-score ≥ –2 sd). One group received weekly alendronic acid and the other group followed a tapering regimen (two doses every 9 months and then two annual doses). Bone turnover markers and BMD were measured before starting Dab, before withdrawing it and one year after withdrawal.

Results

20 patients. 90% (18) women. Mean age: 62.65 years. Mean treatment time of 51.85 (20.11) months. 2 patients with history of osteoporotic fractures. In 9 patients (45%) Dab was tapered and 11 patients (55%) received alendronic acid weekly. There are no differences as long as age, initial BMD or history of osteoporotic fractures between groups. There is a statistically significative reduction in BMD (1.043 ± 0.084 to 0.091 ± 0.093; P = 0.011) and T-score (−1.03 ± 0.43 to −1.63 ± 0.75; P = 0.012) in lumbar spine one year after in the group where Dab was tapered. There are not differences in the evolution of lumbar spine BMD either in the group who received bisphosphonate or in the whole sample. There are neither statistically significative differences in hip BMD in any of the groups, neither globally nor individually. Between groups there are not statistically significative differences in BMD, T-score or percentage of BMD modification one year after Dab withdrawal.

Conclusions

After Dab withdrawal using a bisphosphonate is a safe strategy and it is not associated with BMD loss in our series. In neither of the groups where fractures one year after Dab discontinuation.