LAUSR

OBJECTIVE To explore the value of red blood cell distribution width (RDW) in evaluating the severity of patients infected with novel coronavirus Delta variant. METHODS A total of 28 patients infected with novel coronavirus Delta variant in designated hospital treated by the First Affiliated Hospital of Xi'an Jiaotong University medical team from December 2021 to January 2022 were enrolled (23 cases of common type, 4 severe and 1 critical cases). The detailed clinical data of patients was collected. Then, Pearson's correlation analysis was used to identify the blood examination indexes which affected the arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2). According to the median standard deviation of red blood cell distribution width (RDW-SD, 42.5 fL), 28 patients were divided into low RDW-SD group (≤ 42.5 fL, 16 cases) and high RDW-SD group (> 42.5 fL, 12 cases), and the immune related indexes of the two groups were compared. Receiver operator characteristic curve (ROC) was drawn to evaluate the predictive value of RDW-SD on the severity of illness of coronavirus disease 2019 (COVID-19). RESULTS Correlation analysis showed that RDW-SD was the only index related to PaO2 and PaCO2 on the first day of admission, which was negative correlation with PaO2 (r = -0.379, P = 0.047) and positive correlation with PaCO2 (r = 0.509, P = 0.006). The results of effects of different clinical characteristics on RDW-SD level showed that there was no statistically significant difference in RDW-SD between groups with different clinical characteristics (including male/female, ≥ 65 years old/< 65 years old, having/without hypertension, having/without diabetes, smoking/not smoking, having/without hyperpyrexia, with/without fever for 3 days, with/without respiratory symptoms, with/without digestive symptoms). It was suggested that RDW-SD be relatively stable and not affected by the patient's baseline level. The percentage of B cells in low RDW-SD group was higher than that in high RDW-SD group (23.01±3.01 vs. 15.34±5.34, P < 0.05), immunoglobulin G (IgG) level in low RDW-SD group was lower than that in high RDW-SD group (g/L: 11.43±3.20 vs. 15.42±1.54, P < 0.05). The area under ROC curve (AUC) of RDW-SD in evaluating severe cases was 0.83 [95% confidence interval (95%CI) was 0.59-1.06], which was close to multilobularinltration, hypo-lymphocytosis, bacterial coinfection, smoking history, hyper-tension and age (MuL BSTA score; AUC = 0.82, 95%CI was 0.51-1.12) and better than British Thoracic Society's modified pneumonia score (CURB-65 score; AUC = 0.70, 95%CI was 0.50-0.91). CONCLUSIONS RDW-SD has significant evaluative effect on the severity of COVID-19 patients with Delta variants.