Impact of the COVID-19 Pandemic on Adherence to Denosumab Therapy: A Single Center Study

STUDY DESIGN: A retrospective comparative study of denosumab therapy adherence before and during the coronavirus disease 2019 (COVID-19) pandemic. PURPOSE: To evaluate the effect of the COVID-19 pandemic on denosumab therapy adherence in Japan. OVERVIEW OF LITERATURE: Denosumab is a monoclonal antibody for osteoporosis treatment. Delayed denosumab injections are associated with reduced treatment responses, which was a concern during the COVID-19 pandemic. METHODS: Participants included 376 patients who received denosumab (60 mg every 6 months) from January 2013 to June 2021. The time from therapy initiation to discontinuation was used to measure persistence, and that between initial and subsequent injections was used to determine adherence. The pandemic period was from March 2020 to December 2021. RESULTS: Patients were divided into those treated after March 2020 (pandemic group, n=244) and those who discontinued treatment before March 2020 (non-pandemic group, n=132). Non-persistent cases accounted for 154, including 24 (20%), 64 (19%), and 66 (53%) aged ≤59 years, 60–79 years, and ≥80 years, respectively. The overall persistence rate at 78 months was 59.2%. Postponed cases were significantly lower in the non-pandemic group than in the pandemic group (8% vs. 15%, p=0.042). Postponement with a delay of 1–2 months did not significantly differ between the two groups, but with a significant difference for a delay of ≥3 months (0% vs. 36%, p=0.024). CONCLUSIONS: Denosumab adherence remained constant but postponed cases significantly increased during the COVID-19 pandemic. Better communication by health providers on denosumab adherence and alternative administration may reduce dosing interruptions in similar pandemic situations.