BACKGROUND. Evidence supporting convalescent plasma (CP), one of the first investigational treatments for COVID-19, has been inconclusive, leading to conflicting recommendations. The primary objective was to perform a comparative effectiveness study of CP for all-cause, in-hospital mortality in patients with COVID-19.
METHODS.The multicenter, electronic health records-based, retrospective study included 44,770 patients hospitalized with COVID-19 in one of 176 HCA Healthcare-affiliated community hospitals. Coarsened exact matching (1:k) was employed, resulting in a sample of 3,774 CP and 10,687 comparison patients.
RESULTS.Examination of mortality using a shared frailty model, controlling for concomitant medications, date of admission, and days from admission to transfusion, demonstrated a significant association of CP with lower mortality risk relative to the comparison group (aHR=0.71, 95%CI 0.59-0.86, p<0.001). Examination of patient risk trajectories, represented by 400 clinicodemographic features from our Real-Time Risk Model (RTRM), indicated that patients who received CP recovered quicker. The stratification of days to transfusion revealed that CP within 3 days after admission, but not 4-7 days, was associated with a significantly lower mortality risk (aHR=0.53, 95%CI 0.47-0.60, p<0.001). CP serology level was inversely associated with mortality when controlling for its interaction with days to transfusion (HR=0.998, 95%CI 0.997-0.999, p=0.013) yet not reaching univariable significance.CONCLUSIONS. This large, diverse, multicenter cohort study demonstrated that CP, compared to matched controls, is significantly associated with reduced risk of in-hospital mortality. These observations highlight the utility of real-world evidence and suggest the need for further evaluation prior to abandoning CP as a viable therapy for COVID-19.
