Impact of a Bisphosphonate Drug Holiday on the Bone Mineral Density in Patients with Osteoporosis

Abstract

ABSTRACT Background: Bisphosphonate therapy has proven efficacy in the management of osteoporosis. Unlike other therapies, bisphosphonates are unique in that they continue inhibiting bone resorption after a discontinuation of therapy. Rare adverse effects related to its prolonged use, specifically osteonecrosis of the jaw and atypical femur fractures, resulted in the concept of a “drug holiday” (DH). Objective: To evaluate the effect of a bisphosphonate DH on bone mineral density (BMD) in the treatment of osteoporosis with zoledronic acid and/or alendronate. Methods: A single-centre retrospective cohort study of 97 patients with osteoporosis who had received bisphosphonate therapy and undertaken a DH between 2000 and 2016 was conducted at a large public academic hospital in Johannesburg, South Africa. Results: A total of 97 patients were included in the study. The median age at the initiation of bisphosphonate therapy was 63 years. The median duration of treatment before the DH was 5 years with the median duration of the DH being 2 years. The overall effect of the DH on BMD assessed as the percentage change from the beginning to the end of the DH showed a decrease in BMD lumbar spine [−3.3%, P = 0.398], radius and ulnar [−16.7%, P = 0.03] and total hip [−8.9%, P = 0.001]. Four patients (4.1%) sustained fractures during the DH. Conclusion: A DH should be cautiously considered with the long-term use of bisphosphonates. An individualised approach based on risk factor assessment, fracture risk, and BMD is key in assessing the duration of the DH, and only low-risk patients should be considered.