Association between red blood cell distribution width and mortality of COVID-19 patients

We have previously reported an association between high red blood cell distribution width (RDW) and mortality in septic and brain infarction patients. However, no association between RDW and mortality in coronavirus disease 2019 (COVID-19) patients has been reported so far; thus, the objective of this study was to determine if that association exists.

Prospective and observational study carried out in 8 Intensive Care Units from 6 hospitals of Canary Islands (Spain) including COVID-19 patients. We recorded RDW at ICU admission and 30-day survival.

We found that patients who did not survive (n=25) compared to surviving patients (n=118) were older (p=0.004), showed higher RDW (p=0.001), urea (p<0.001), APACHE-II (p<0.001) and SOFA (p<0.001), and lower platelet count (p=0.007) and pH (p=0.008). Multiple binomial logistic regression analysis showed that RDW was associated with 30-day mortality after controlling for: SOFA and age (OR=1.659; 95% CI=1.130-2.434; p=0.01); APACHE-II and platelet count (OR=2.062; 95% CI=1.359-3.129; p=0.001); and pH and urea (OR=1.797; 95% CI=1.250-2.582; p=0.002). The area under the curve (AUC) of RDW for mortality prediction was of 71% (95% CI=63-78%; p<0.001). We did not find significant differences in the predictive capacity between RDW and SOFA (p=0.66) or between RDW and APACHE-II (p=0.12).

Our study provides new information regarding the ability to predict mortality in patients with COVID-19. There is an association between high RDW and mortality. RDW has a good performance to predict 30-day mortality, similar to other severity scores (such as APACHE II and SOFA) but easier and faster to obtain.