Influence of bamlanivimab administration timing relative to symptoms on hospital revisit

Introduction: Bamlanivimab is a monoclonal antibody treatment for mild-to-moderate coronavirus disease 2019 (Covid-19) in patients at high risk for severe disease progression and/or hospitalization. Despite emerging evidence that bamlanivimab plus etesevimab decreases viral load more than monotherapy, there is insufficient evidence of bamlanivimab monotherapy's effects on 28-day all-cause hospital revisit and adverse drug reactions (ADRs) considering its widespread use. Research Question or Hypothesis: Does bamlanivimab administration within 3 days of symptom onset have a lower 30-day revisit rate versus later administration? Study Design: Single-center, retrospective cohort study Methods: The electronic medical record was queried for all consecutive patients who received bamlanivimab in a 2-month period. The primary outcome was 30-day post infusion revisit rate in patients who presented in < 3 days (early) versus ≥ 3 days (later) of symptom onset. Secondary outcomes included Covid-19- and ADR-related rates of revisit and 30-day hospital admission rate between groups. Chi-square and independent samples t-test were used to compare categorical and continuous data, respectively. Results: 183 patients met the inclusion criteria and were included in the analysis. There were 70 patients with early administration and 113 with later administration. Baseline characteristics for both groups were similar. The average age was 67 years and BMI 30 mg/m2;proportions of active smokers was roughly 4.5% and patients with diabetes were 30%. Early and late administration of bamlanivimab were alike in terms of any hospital revisit (21.4% vs. 22.1%;p=0.912). Similarly, there was no significant between group difference for COVID-19 or ADR related revisits as well as for Covid-19 hospital admission within 30 days. No variables predictive of 30-day hospital revisit were identified. Conclusion: We did not find any difference in outcomes between early and late administration of bamlanivimab. The hospital admission rate was similar to previous studies.