Efficacy and harms of convalescent plasma for treatment of hospitalized COVID-19 patients: a systematic review and meta-analysis

Abstract

Introduction We systematically reviewed benefits and harms of convalescent plasma (CP) in hospitalized COVID-19 patients. Material and methods Randomized controlled trials (RCTs) and observational studies assessing CP effects on hospitalized, adult COVID-19 patients were searched until November 24, 2020. We assessed risk of bias (RoB) using Cochrane RoB 2.0 and ROBINS-I tools. Inverse variance random effect meta-analyses were performed. Quality of evidence was evaluated using GRADE methodology. Primary outcomes were all-cause mortality, clinical improvement, and adverse events. Results Five RCTs (n = 1067) and 6 cohorts (n = 881) were included. Three and 1 RCTs had some concerns and high RoB, respectively; and there was serious RoB in all cohorts. Convalescent plasma did not reduce all-cause mortality in RCTs of severe (RR = 0.60, 95% CI: 0.33–1.10) or moderate (RR = 0.60, 95% CI: 0.09–3.86) COVID-19 vs. standard of care (SOC); CP reduced all-cause mortality vs. SOC in cohorts (RR = 0.66, 95% CI: 0.49–0.91). Convalescent plasma did not reduce invasive ventilation vs. SOC in moderate disease (RR = 0.85, 95% CI: 0.47–1.55). In comparison to placebo + SOC, CP did not affect all-cause mortality (RR = 0.75, 95% CI: 0.48–1.16) or clinical improvement (HR = 1.07, 95% CI: 0.82–1.40) in severe patients. Adverse and serious adverse events were scarce, similar between CP and controls. Quality of evidence was low or very low for most outcomes. Conclusions In comparison to SOC or placebo + SOC, CP did not reduce all-cause mortality in RCTs of hospitalized COVID-19 patients. Convalescent plasma did not have an effect on other clinical or safety outcomes. Until now there is no good quality evidence to recommend CP for hospitalized COVID-19 patients.