Red cell distribution width is a potent prognostic parameter for in-hospital and post-discharge mortality in hospitalized coronavirus disease 2019 patients: a registry-based cohort study on 3941 patients

Aim To investigate clinical and prognostic associations of red cell distribution width (RDW) in hospitalized coronavi - rus disease 2019 (COVID-19) patients. Methods We retrospectively analyzed the records of 3941 consecutive COVID-19 patients admitted to a tertiary-level institution from March 2020 to March 2021 who had avail - able RDW on admission. Results The median age was 74 years. The median Charl - son comorbidity index (CCI) was 4. The majority of pa - tients (84.1%) on admission presented with severe or criti - cal COVID-19. Patients with higher RDW were significantly more likely to be older and female, to present earlier dur - ing infection, and to have higher comorbidity burden, worse functional status, and critical presentation of COVID-19 on admission. RDW was not significantly associated with C-re - active protein, occurrence of pneumonia, or need for oxy - gen supplementation on admission. During hospital stay, patients with higher RDW were significantly more likely to require high-flow oxygen therapy, mechanical ventilation, intensive care unit, and to experience prolonged immobi - lization, venous thromboembolism, bleeding, and bacte - rial sepsis. Thirty-day and post-hospital discharge mortality gradually increased with each rising RDW percent-point. In a series of multivariate Cox-regression models, RDW demon - strated robust prognostic properties at >14% cut-off level. This cut-off was associated with inferior 30-day and postdischarge survival independently of COVID-19 severity, age, and CCI; and with 30-day survival independently of COVID severity and established prognostic scores (CURB-65, 4Cmortality, COVID-gram and VACO-index). Conclusion RDW has a complex relationship with COVID19-associated inflammatory state and is affected by prior comorbidities. RDW can improve the prognostication in hospitalized COVID-19 patients.