Purpose:​ To evaluate the impact of the COVID lock-down on treatment interruptions of romosozumab, a first in class biologic therapy, administered by healthcare providers once monthly.

Methods:​ We used Medicare data from 1/1/2017 to 9/30/2021 to identify women age ≥65 initiating romosozumab between 4/1/2019 and 6/30/2021. Patient demographics, provider specialty, and baseline comorbidities were identified. Romosozumab dispensations were grouped into five 6-month periods based on the dispensing date from FDA licensure to the end of the data (Period 1 to 5). “Treatment interruption” was defined as any interval gap between 2 dispensations >60 days. The numbers of treatment interruption event were aggregated per period per patient. Mixed effect Poisson regression with patient-level random effects was performed, including an interaction term between Period and number of prior doses.

Results:​ There were 12,216 romosozumab new users identified. A total of 2724 treatment interruption events were identified among 2229 romosozumab users. After adjustment, comparing with the period immediately before the lockdown (Period 2:​ 2019-10-1–2020-3-30), the IRRs (95 % CI) for treatment interruption were 0.49 (0.29, 0.81), 1.65 (1.48, 1.85), 1.79 (1.60, 2.01), and 1.67 (1.49, 1.87) for periods 1, 3, 4, and 5, respectively, per 1 prior dose change (p < 0.01 for all IRRs), where Periods 3, 4, and 5 were post-lockdown.

Conclusion:​ Compared to the pre-COVID period, the lockdown negatively impacted the continuity of romosozumab treatment among Medicare beneficiaries. Prioritizing in-time assistance for patients receiving a provider-administered parenteral therapy is critical when patients' in-person access to their provider is compromised.