Blood type and outcomes in patients with COVID-19.

This study aimed to determine if there is an association between ABO blood type and severity of COVID-19 defined by intubation or death as well as ascertain if there is variability in testing positive for COVID-19 between blood types. In a multi-institutional study, all adult patients who tested positive for COVID-19 across five hospitals were identified and included from March 6th to April 16th, 2020. Hospitalization, intubation, and death were evaluated for association with blood type. Univariate analysis was conducted using standard techniques and logistic regression was used to determine the independent effect of blood type on intubation and/or death and positive testing. During the study period, there were 7648 patients who received COVID-19 testing throughout the institutions. Of these, 1289 tested positive with a known blood type. A total of 484 (37.5%) were admitted to hospital, 123 (9.5%) were admitted to the ICU, 108 (8.4%) were intubated, 3 (0.2%) required ECMO, and 89 (6.9%) died. Of the 1289 patients who tested positive, 440 (34.2%) were blood type A, 201 (15.6%) were blood type B, 61 (4.7%) were blood type AB, and 587 (45.5%) were blood type O. On univariate analysis, there was no association between blood type and any of the peak inflammatory markers (peak WBC, p = 0.25; peak LDH, p = 0.40; peak ESR, p = 0.16; peak CRP, p = 0.14) nor between blood type and any of the clinical outcomes of severity (admission p = 0.20, ICU admission p = 0.94, intubation p = 0.93, proning while intubated p = 0.58, ECMO p = 0.09, and death p = 0.49). After multivariable analysis, blood type was not independently associated with risk of intubation or death (referent blood type A; blood type B: AOR: 0.72, 95% CI: 0.42-1.26, blood type AB: AOR: 0.78, CI: 0.33-1.87, blood type O: AOR: 0.77, CI: 0.51-1.16), rhesus factor positive (Rh+): AOR: 1.03, CI: 0.93-1.86. Blood type A had no correlation with positive testing (AOR: 1.00, CI: 0.88-1.13), blood type B was associated with higher odds of testing positive for disease (AOR: 1.28, CI: 1.08-1.52), AB was also associated with higher odds of testing positive (AOR: 1.37, CI: 1.02-1.83), and O was associated with a lower risk of testing positive (AOR: 0.84, CI: 0.75-0.95). Rh+ status was associated with higher odds of testing positive (AOR: 1.23, CI: 1.003-1.50). Blood type was not associated with risk of intubation or death in patients with COVID-19. Patients with blood types B and AB who received a test were more likely to test positive and blood type O was less likely to test positive. Rh+ patients were more likely to test positive.