Mortality rates among hospitalized patients with COVID-19 treated with convalescent plasma A Systematic review and meta-analysis

IMPORTANCEMany hospitalized patients with COVID-19 have been treated with convalescent plasma. However, it is uncertain whether this therapy lowers mortality and if so, if the mortality benefit is larger among specific subgroups, such as recipients of plasma with high antibody content and patients treated early in the disease course.OBJECTIVETo examine the association of COVID-19 convalescent plasma transfusion with mortality and the differences between subgroups in hospitalized patients with COVID-19.DATA SOURCESOn October 26, 2022, a systematic search was performed for clinical studies of COVID-19 convalescent plasma in the literature.STUDY SELECTIONRandomized clinical trials and matched cohort studies investigating COVID-19 convalescent plasma transfusion compared with standard of care treatment or placebo among hospitalized patients with confirmed COVID-19 were included. The electronic search yielded 3,841 unique records, of which 744 were considered for full-text screening. The selection process was performed independently by a panel of five reviewers.DATA EXTRACTION AND SYNTHESISThe study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data were extracted by 5 independent reviewers in duplicate and pooled using inverse-variance random-effects model.MAIN OUTCOMES AND MEASURESPrespecified end point was all-cause mortality during hospitalization.RESULTSThirty-nine randomized clinical trials enrolling 21,529 participants and 70 matched cohort studies enrolling 50,160 participants were included in the systematic review. Separate meta-analyses demonstrated that transfusion of COVID-19 convalescent plasma was associated with a significant decrease in mortality compared with the control cohort for both randomized clinical trials (odds ratio (OR), 0.87 [95% CI, 0.76-1.00]) and matched cohort studies (OR, 0.77 [95% CI, 0.64-0.94]). Meta-analysis of subgroups revealed two important findings. First, treatment with convalescent plasma containing high antibody levels was associated with a decrease in mortality compared to convalescent plasma containing low antibody levels (OR, 0.85 [95% CI, 0.73 to 0.99]). Second, earlier treatment with COVID-19 convalescent plasma was associated with a significant decrease in mortality compared with the later treatment cohort (OR, 0.63 [95% CI, 0.48 to 0.82]).CONCLUSIONS AND RELEVANCECOVID-19 convalescent plasma use was associated with a 13% reduced risk in mortality, implying a mortality benefit for hospitalized patients with COVID-19, particularly those treated with convalescent plasma containing high antibody levels treated earlier in the disease course.Key PointsQuestionWhat is the evidence regarding the potential mortality benefit associated with transfusion of convalescent plasma in hospitalized patients with COVID-19?FindingsIn this meta-analysis of 39 randomized clinical trials enrolling 21,529 participants and 70 matched cohort studies enrolling 50,160 participants, transfusion of convalescent plasma was associated with a 13% mortality benefit. Subgroup analyses revealed that patients treated with plasma containing higher levels of antibodies and patients treated earlier in the course of the disease had a greater mortality benefit associated with COVID-19 convalescent plasma transfusion.MeaningThese findings suggest that transfusion of COVID-19 convalescent plasma is associated with a mortality benefit for hospitalized patients, particularly those treated earlier in the disease course.