BACKGROUND: COVID-19 has strained healthcare systems with patient hospitalizations and deaths. Anti-spike monoclonal antibodies, including bamlanivimab, have demonstrated reduction in hospitalization rates in clinical trials, yet real-world evidence is lacking. METHODS: We conducted a retrospective case-control study across a single healthcare system of non-hospitalized patients, age 18 years or older, with documented positive SARS-CoV-2 testing, risk factors for severe COVID-19, and referrals for bamlanivimab via emergency use authorization. Cases were defined as patients who received bamlanivimab; contemporary controls had a referral order placed but did not receive bamlanivimab. The primary outcome was 30-day hospitalization rate from initial positive SARS-CoV-2 PCR. Descriptive statistics, including Chi-square and Mann-Whitney U test, were performed. Multivariable logistic regression was used for adjusted analysis to evaluate independent associations with 30-day hospitalization. RESULTS: Between November 20, 2020 and January 19, 2021, 218 patients received bamlanivimab (cases) and 185 were referred but did not receive drug (controls). Thirty-day hospitalization rate was significantly lower among patients who received bamlanivimab (7.3% v 20.0%, RR 0.37, 95% CI 0.21-0.64, p<0.001), and the number needed to treat was 8. On logistic regression, odds of hospitalization were increased in patients not receiving bamlanivimab and with a higher number of pre-specified comorbidities (OR 4.19 CI: 1.31-2.16, p<0.001; OR 1.68, CI: 2.12-8.30, p<0.001, respectively). CONCLUSION: Ambulatory patients with COVID-19 who received bamlanivimab had a lower 30-day hospitalization than control patients in real-world experience. We identified receipt of bamlanivimab and fewer comorbidities as protective factors against hospitalization.
Real-World Experience of Bamlanivimab for COVID-19: A Case-Control Study