Association between blood groups and clinical outcomes in critically ill COVID-19 patients: A retrospective study

Abstract

Introduction: A small proportion of patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) become critically ill. Individuals’ blood group may influence their susceptibility to infection. However, the relationship between blood groups and clinical outcomes in severe Coronavirus disease 2019 (COVID-19) is not well established. Therefore, we conducted a study to investigate the association between blood groups and clinical outcomes in critically ill COVID-19 patients. Methods: We retrospectively analyzed electronic health records of COVID-19 patients admitted to intensive care units (ICUs) at Hazm Mebaireek General Hospital, Qatar, from March 7th, 2020, to July 15th, 2020. The study population was divided based on their blood groups into types A, B, AB, O, Rhesus (Rh)-positive, and Rh-negative. The primary outcome studied in each blood group was all-cause ICU mortality. Secondary outcomes evaluated were the requirement and duration of mechanical ventilation, ICU days, hospitalization days, and C-reactive protein (CRP) value on admission. Results: Eight hundred forty-eight patients were admitted to ICUs with severe COVID-19 during the study period. All-cause ICU mortality in the study population was 19.8% (168/848), and that in individuals with blood groups A, B, AB, O, Rh-positive, and Rh-negative was 22.6% (52/230), 18.1% (44/243), 22% (18/82), 18.4% (54/293), 20.4% (165/810), and 7.9% (3/38). Although the highest mortality was noted in blood group A, followed by AB, these observations failed to achieve statistical significance. Rh-negative blood type had lower odds of death compared to the Rh-positive one (odds ratio = 0.27; 95% confidence interval 0.08–0.99, P = 0.049). None of the blood groups showed an association with the need for mechanical ventilation, duration of mechanical ventilation, duration of ICU and hospital stay, and CRP value on admission. Conclusion: This study revealed no association between ABO blood groups and unfavorable clinical outcomes in critically ill COVID-19 patients. The Rh-negative blood type was associated with slightly lower odds of death compared to the Rh-positive one.