Objective:

To explore the relation between ABO blood group system and in-hospital mortality in Mexican patients admitted with COVID-19.

Materials and methods:

We performed a retrospective study with 2,369 hospitalized patients with confirmed SARS-CoV-2 infection in a tertiary referral hospital, admitted between March 27 and December 10, 2020. Data were obtained from electronic health records. Adjusted and unadjusted Cox Proportional-Hazard models were performed to test the association of ABO blood groups with mortality of COVID-19 patients. The variables considered for adjustment of the models were age, sex, and main comorbidities.

Results:

Out of all studied patients, group O was the most frequent blood type with 1999 patients (84.3%), followed by group A (11.3%), B (3.5%) and AB (0.72%). Blood group A was associated with a lower hazard of death among COVID-19 patients compared with group O (adjusted HR = 0.72, 95% IC 0.55-0.95, P = 0.02. Groups B, AB and Positive Rh were not significantly associated with the outcome.

Conclusions:

We found evidence of a statistically significant association between ABO blood type and COVID-19 in-hospital death. Patients with blood group A may be less likely to die during hospitalization compared with group O.