Real-world effectiveness of casirivimab and imdevimab among patients diagnosed with COVID-19 in the ambulatory setting: a retrospective cohort study using a large claims database.

OBJECTIVE: To assess the real-world effectiveness of casirivimab and imdevimab (CAS+IMD) versus no COVID-19 antibody treatment among patients diagnosed with COVID-19 in the ambulatory setting, including patients diagnosed during the Delta-dominant period prior to Omicron emergence. DESIGN: Retrospective cohort study. SETTING: Komodo Health closed claims database. PARTICIPANTS: 13 273 128 patients diagnosed with COVID-19 (December 2020 through September 2021) were treated with CAS+IMD or untreated but treatment eligible under the Emergency Use Authorization (EUA). Each treated patient was exact and propensity score matched without replacement to up to five untreated EUA-eligible patients. INTERVENTIONS: CAS+IMD. PRIMARY AND SECONDARY OUTCOME MEASURES: Composite endpoint of 30-day all-cause mortality or COVID-19-related hospitalisation. Kaplan-Meier estimators were used to calculate outcome risks overall and across subgroups: age, COVID-19 vaccination status, immunocompromised status, and timing of diagnosis (December 2020 to June 2021, and July to September 2021). Cox proportional hazards models were used to estimate adjusted HRs (aHRs) and 95% CIs. RESULTS: Among 75 159 CAS+IMD-treated and 1 670 338 EUA-eligible untreated patients, 73 759 treated patients were matched to 310 688 untreated patients; matched patients were ~50 years, ~60% were women and generally well balanced across risk factors. The 30-day risk of the composite outcome was 2.1% and 5.2% in the CAS+IMD-treated and CAS+IMD-untreated patients, respectively; equivalent to a 60% lower risk (aHR 0.40; 95% CI, 0.38 to 0.42). The effect of CAS+IMD was consistent across subgroups, including those who received a COVID-19 vaccine (aHR 0.48, 95% CI, 0.41 to 0.56), and those diagnosed during the Delta-dominant period (aHR 0.40, 95% CI, 0.38 to 0.42). CONCLUSIONS: The real-world effectiveness of CAS+IMD is consistent with the efficacy for reducing all-cause mortality or COVID-19-related hospitalisation reported in clinical trials. Effectiveness is maintained across patient subgroups, including those prone to breakthrough infections, and was effective against susceptible variants including Delta. .

Effectiveness of Subcutaneous Casirivimab and Imdevimab in Ambulatory Patients with COVID-19.

INTRODUCTION: Data on real-world effectiveness of subcutaneous (SC) casirivimab and imdevimab (CAS+IMD) for the treatment of coronavirus disease 2019 (COVID-19) are limited. The objective of this study was to assess the effectiveness of SC CAS+IMD versus no antibody treatment among patients with COVID-19. METHODS: This retrospective cohort study linked Komodo Health and CDR Maguire Health and Medical data. Patients diagnosed with COVID-19 in ambulatory settings (August 1-October 30, 2021) treated with SC CAS+IMD were exact- and propensity score-matched to fewer than five untreated treatment-eligible patients and followed for the composite endpoint of 30-day all-cause mortality or COVID-19-related hospitalization. Kaplan-Meier estimators were used to calculate outcome risk overall and across subgroups. Cox proportional-hazards models were used to estimate adjusted hazard ratios (aHR) and 95% confidence intervals (CI). RESULTS: Of 13,522 patients treated with CAS+IMD, 12,972 were matched to 41,848 untreated patients. The 30-day composite outcome risk was 1.9% (95% CI 1.7-2.2) and 4.4% (95% CI 4.2-4.6) in the treated and untreated cohorts, respectively; treated patients had a 49% lower relative risk of the composite outcome (aHR 0.51; 95% CI 0.46-0.58) and a 67% relative risk of 30-day mortality (aHR 0.33, 95% CI 0.18-0.60). Effectiveness was consistent across vaccination status and various subgroups. DISCUSSION: Patients with COVID-19 benefitted from treatment with SC CAS+IMD versus untreated patients. The results were consistent across subgroups of patients, including older adults, immunocompromised patients, and patients vaccinated against COVID-19. Results were robust across numerous sensitivity analyses. CONCLUSION: SC CAS+IMD is effective in reducing 30-day COVID-19-related hospitalization or mortality in real-world outpatient settings during the Delta-dominant period.