ABO Blood Group and RhD status Are Not Associated with Mortality and Morbidity in Critically Ill Patients; a Multicentre Observational Study of 29 512 Patients
Abstract Background. Previous studies have demonstrated an association between ABO blood groups and many types of disease. The present study primarily aimed to identify associations between ABO blood groups, RhD groups and mortality/morbidity outcomes in critically ill patients both in a main cohort and in six pre-defined subgroups. The secondary aim was to investigate any differences in transfusion requirement between the different ABO blood groups and RhD status.Methods. Adult patients admitted to any of the five intensive care units (ICUs) in Skåne, Sweden, between February 2007 and April 2021 were eligible for inclusion. The outcomes were mortality analysed at 28– and 90–days as well as at the end of observation and morbidity measured using days alive and free of (DAF) invasive ventilation (DAF ventilation) and DAF circulatory support, including vasopressors or inotropes (DAF circulation), maximum Sequential Organ Failure Assessment score (SOFAmax) the first 28 days after admission and length of stay. All outcomes were analysed in separate multivariable regression models (adjusted for age and sex), generating odds or hazard ratios for each blood group and RhD status using blood group O and RhD negative as reference. Transfusion requirements were also investigated.Results. In total, 29 512 unique patients were included in the analyses. There were no significant differences for any of the outcomes between non-O blood groups and blood group O, or between RhD groups. In five pre-defined subgroups (sepsis, septic shock, acute respiratory distress syndrome, cardiac arrest and trauma) there were no differences in mortality between non-O blood groups and blood group O or between the RhD groups. The Covid-19 cohort was not investigated given the low number of patients. Furthermore, we could not demonstrate any differences in the number of transfused patients between the ABO blood groups or between the RhD groups.Conclusions. ABO blood type and RhD status do not appear to influence mortality or morbidity in a general critically ill patient population. There were no differences in the number of transfused patients between the ABO blood groups or between the RhD status groups.