Association Between Rhesus and ABO Blood Group Types and Their Impact on Clinical Outcomes in Critically Ill Patients with COVID-19: A Multi-Center Investigation.

Background: There is increasing evidence suggesting that ABO blood type may play a role in the immunopathogenesis of COVID-19 infection. In addition to ABO blood type, the Rhesus (Rh) factor has also been implicated in various disease processes. Therefore, our study aimed to assess the association between both ABO and Rh blood types in critically ill patients with COVID-19 and their clinical outcomes. Methods: A multicenter retrospective cohort study conducted in Saudi Arabia between March 1, 2020, and July 31, 2021, involving adult COVID-19 patients admitted to Intensive Care Units, aimed to explore potential associations between rhesus blood group types (Positive versus Negative) and clinical outcomes. The primary endpoint assessed was the hospital length of stay (LOS). Other endpoints were considered secondary. Results: After propensity score matching (3:1 ratio), 212 patients were included in the final analysis. The hospital length of stay was longer in a negative Rh blood group compared with patients in the Rh-positive group (beta coefficient 0.26 (0.02, 0.51), p = 0.03). However, neither 30-day mortality (HR 0.28; 95% CI 0.47, 1.25, p = 0.28) nor in-hospital mortality (HR 0.74; 95% CI 0.48, 1.14, p = 0.17) reached statistical significance. Additionally, among the different ABO types, the A+ blood group exhibited a higher proportion of thrombosis/infarction and in-hospital mortality (28.1% and 31.2%, respectively). Conclusion: This study highlights the potential impact of blood group type on the prognosis of critically ill patients with COVID-19. It has been observed that patients with a negative Rh blood group type tend to have a longer hospital stay, while their mortality rates and complications during ICU stay are similar to the patients with a Rh-positive group.