Red Blood Cell Distribution Width Is Not a Predictor of Hospital Mortality in Elderly and Nonelderly COVID‐19‐Infected Patients: A Prospective Study at a Brazilian Quaternary University Hospital

<b>Objective:</b> To investigate if red blood cell distribution width (RDW) is a risk factor for hospital mortality in patients admitted to a public university hospital in Belo Horizonte, Minas Gerais, Brazil. <b>Methods:</b> This observational prospective study included patients over 16 years who had been hospitalized for COVID-19 between May and October 2020. A descriptive and time-to-death analysis was performed using the Cox proportional hazards model. <b>Results:</b> Of the 161 patients included, 39 (24.2%) died during hospitalization. A total of 2227 blood counts were performed, an average of 13.8 tests per patient (standard deviation, SD 2.9). Upon admission, the RDW was normal (11.5% to 14.6%) in 115 patients (71.4%), elevated in 45 (28%), and low in 1 (0.6%). The mean RDW value at admission was 14.5 (SD 2.4), which falls within the normal reference range. Of the patients with normal RDW at admission, 82 (71.3%) maintained normal levels throughout their stay, while 33 (28.7%) showed increased RDW levels over time. Among those with elevated RDW at admission, 40 (88.9%) remained elevated, while 5 (11.1%) returned to normal levels. There was no significant difference in the mean RDW value at admission between survivors and nonsurvivors (14.4 [SD 2.4] for survivors vs. 14.9 [SD 2.4] for nonsurvivors; <i>p</i>=0.2081). The risk for mortality in the group with high RDW upon admission was higher than in the group with normal RDW, but without statistical significance (31.1% vs. 21.7%; RR = 1.43; <i>p</i>=0.413). When performing a multivariate analysis, the following continue to be risk factors for lower survival: age > 70 years, HR 4.8 (95% CI: 2.3; 10.3), <i>p</i> < 0.001; white race, HR 3.2 (95% CI: 1.2; 8.61), <i>p</i>=0.018; and need for invasive MV, HR 3.8 (1.7; 8.7), <i>p</i>=0.001. The presence of a chest X-ray suggestive of COVID-19, HR 3.5 (95% CI: 1.0; 11.5), <i>p</i>=0.044, also appears to be a risk factor in this analysis. <b>Conclusion:</b> Alterations on RDW values on admission were not associated with higher mortality, and further increases in RDW during hospitalization were not linked to a higher risk of mortality across all age groups. Our findings suggest that while RDW may indicate disease severity, it may not serve as a reliable independent predictor of mortality when other factors are accounted for in this cohort.