Red cell distribution width is associated with mortality in non‐anemic patients with COVID‐19

Rapp, Joseph L.; Tremblay, Douglas; Alpert, Naomi; Lieberman‐Cribbin, Wil; Mascarenhas, John; Taioli, Emanuela; Ghaffari, Saghi

INTRODUCTION We have read with great interest the meta-analysis that examined the impact of increased red cell distribution width (RDW) and COVID-19 outcomes, conducted by Lee and colleagues, and recently published in the Journal of Medical Virology. The authors concluded that elevations in RDW were associated with adverse COVID-19 outcomes. However, the impact of elevation of RDW independent of anemia in COVID-19 remains to be clarified. METHODS Patients ≥18 years who were diagnosed with COVID-19 at the Mount Sinai Health System between March 1 and April 1, 2020 and had a complete blood count (CBC) at presentation (n=2562) were selected to assess the association between RDW and mortality. Multivariable Cox proportional hazards regression models, stratified by presence of anemia, were performed to assess the independent association of RDW with mechanical ventilation and mortality. RESULTS At univariate analysis, elevated RDW was statistically significantly associated with mechanical ventilation (p = 0.0109) and mortality (p < 0.0001). We found that elevated RDW was statistically associated with higher risk of both being placed on a ventilator (HRadj: 1.66, 95% CI: 1.19-2.32) and mortality (HRadj: 1.60, 95% CI: 1.18-2.15) in non-anemic patients, but there was no association in anemic patients. These associations were independent of the effects of age, sex, race, and CCI. DISCUSSION In this study, we show that the elevated RDW association with mortality and mechanical ventilation is present exclusively in non-anemic patients. Therefore, we propose that RDW be considered by clinicians, especially in non-anemic patients, when risk-stratifying COVID-19 patients. This article is protected by copyright. All rights reserved.