Importance: Interventions to reduce hospitalization of patients with COVID-19 are urgently needed. Randomized trials for efficacy suggest that anti-SARS-CoV2 neutralizing monoclonal antibodies (MAb) may reduce medically-attended visits and hospitalization but effectiveness has not been confirmed in a real-world setting.
Objective: Estimate the effectiveness of MAb infusion in a real-world cohort of ambulatory patients with early symptomatic COVID-19 at high risk for hospitalization.
Design: Quasi-experimental observational cohort study using target trial emulation and causal inference methodology in pre-and post-implementation groups.
Setting: Infusion centers and urgent care clinics within an integrated healthcare system in the United States
Participants: 13,534 high-risk adult outpatients with symptomatic, laboratory-confirmed COVID-19 within 7 days of symptom onset.
Exposures: A single intravenous infusion of either bamlanivimab 700 mg or casirivimab/imdevimab 1200 mg/1200 mg.
Main Outcomes and Measures: The primary outcome was emergency department visit or hospitalization within 14 days of positive test. Patients who received MAb infusion were compared to contemporaneous controls using inverse probability of treatment weighting, and to a pre-implementation cohort using propensity-weighted interrupted time series analysis. An exploratory analysis compared effectiveness of casirivimab/imdevimab and bamlanivimab.
Results: 7404 patients who would have been MAb-eligible were identified in a pre-implementation cohort (July 1-November 27, 2020). In the post-implementation period (November 28, 2020-January 28, 2021), 594 received MAb treatment and 5536 MAb-eligible patients did not. Among Mab recipients, 479 (80.6%) received bamlanivimab and 115 (19.4%) casirivimab/imdevimab. The primary outcome occurred in 75 (12.6%) MAb recipients, 1018 (18.4%) contemporaneous controls, and 1525 (20.6%) patients in the pre-implementation cohort. MAb treatment was associated with fewer subsequent emergency department visits and hospitalizations (odds ratio estimating the average treatment effect 0.69, 95% CI 0.60-0.79). After implementation, propensity-weighted probability of emergency department visit or hospitalization decreased by 0.7% per day (95% CI 0.03-0.10%, p<0.001). Overall, 7 (1.2%) MAb patients experienced an adverse event; two (0.3%) were considered serious. In the exploratory analysis, the effect of casirivimab/imdevimab versus bamlanivimab was not significant (OR 0.52, 95% CI 0.17-1.63, p=0.26).
Conclusions and Relevance: MAb treatment of high-risk ambulatory patients with early COVID-19 was well-tolerated and effective at preventing the need for subsequent medically-attended care.
Comparative clinical effectiveness of various 5-HT3 RA antiemetic regimens on chemotherapy-induced nausea and vomiting associated with hospital and emergency department visits in real world practice