1. Transfusion of high-titer convalescent antibody plasma was associated with a lower risk of death from coronavirus disease 2019 (COVID-19), compared to low-titered transfusions.
2. The mortality benefit of convalescent plasma antibodies was only observed in patients during earlier stages of the disease.
Evidence Rating Level: 2 (Good)
Study Rundown: During the current COVID-19 pandemic, convalescent plasma containing anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibodies received an emergency-use authorization from the FDA to treat hospitalized COVID-19 patients. This retrospective cohort study aimed to examine the use of convalescent plasma antibodies to treat hospitalized COVID-19 patients. The study determined transfusions containing higher titers of anti-SARS-CoV-2 IgG were associated with a lower risk of death from COVID-19 within 30 days from diagnosis, compared to lower-titered transfusions. Furthermore, earlier administration of convalescent plasma – within 3 days after diagnosis – was also correlated with lower mortality risk, as compared to later transfusions. Study limitations include limited participation, limited information on simultaneous medications and transfusion, and open-label experimental design. Nonetheless, the study was significant as it demonstrated the mortality benefit of high-titered early transfusion of convalescent plasma in a large cohort of severe COVID-19 patients.
In-Depth [retrospective cohort]: This retrospective study was based on a national registry of 3,082 patients from 680 acute care facilities across the United States. Patients included in the study had a high risk of progression to severe COVID-19 based on clinical risk factors such as respiratory failure, blood oxygen desaturation, lung infiltrates, and septic shock. Patients who received more than one transfusion of convalescent plasma were excluded from the study. The primary outcome examined was the mortality rate at 30 days after the plasma transfusion. Overall, the study observed the high-titer group had a lower risk of death within 30 days of transfusion relative to the low-titer group (relative risk [RR], 0.75; 95% confidence interval [CI], 0.61 to 0.93). In addition to antibody titers, earlier administration of convalescent plasma conferred a lower risk of death compared to patients who received transfusions after 4 or more days post-diagnosis (RR, 1.18; 95% CI, 1.04 to 1.35). Overall, this study demonstrated the mortality benefit of early transfusion of high-titered convalescent plasma for hospitalized COVID-19 patients.
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