Predictive factors for intensive care unit length of stay in COVID-19 patients treated with convalescent plasma

ABSTRACT

Background/Case Studies Convalescent plasma (CP) has emerged in the past months as an alternative treatment for COVID-19. We prospectively analysed the outcomes of critically ill COVID-19 patients treated with CP in order to investigate predictive factors of intensive care unit (ICU) length of stay at a single center in Brazil. Study Design/Methods: Thirty COVID-19 patients laboratory-confirmed by RTPCR with severe pneumonia were recruited at a single center in Brazil. Doses of 300-600ml of CP were administered. Primary outcomes were ICU length of stay and duration of mechanical ventilation support.The following variables were analysed Severity organ failure assessment score(SOFA) at day 0 (day of CP transfusion), patient ABO blood group, concomitant use of any other therapies (hydroxychloroquine, azythromicin, tocilizumab, immunoglobulin), neutralizing antibody titers of the patients prior to transfusion (NAbsP) and total titers of neutralizing antibody from CP units transfused (NAbsCP). NAbsCP considers the total amount of antibodies transfused to account for volume differences. Multivariate logistic regression was performed. Results/Findings: In our case series, SOFA at day 0, ABO group, and both NAbs P and NAbsCP were predictive factors of ICU length of stay. At each point increased in SOFA, ICU length of stay was 38.7% longer (MR 1.387 CI 95% 1.254-1.534, p<0.001). Group A had36.1% longer ICU length of stay (MR 0.639 CI 95% 0.417-0.980, p 0.04). Increases of 100 units in NAbsP resulted in 1% reduction of ICU lenght of stay (MR 0.990 CI 95% 0.982-0.998, p 0.017). Similar results were obtained with NAbs-CP, with 2% reduction in ICU length of stay (MR 0.980 CI95% 0.968-0.993, p 0.002) at each 100 unit increase. Use of other therapies did not influence ICU lenght of stay (p 0.373). We perform the same analysis for duration of mechanical ventilation support, and all the variables failed to demonstrate any association Conclusions: Our findings suggest that severity of disease prior to transfusion, ABO group, patient capacity to produce neutralizing antibodies and transfusion of CP with high titer NAbs are significant predictive factors for ICU length of stay. High titer NAbs CP may add benefit to these patients. No association was found between these same variables and duration of mechanical ventilation.