Predictive Value of Neutrophil-to-Lymphocyte Ratio at Admission for Chest X-Ray Progression in Hospitalized COVID-19 Patients

Objective: Previous studies focused on using the neutrophil-to-lymphocyte ratio (NLR) to monitor COVID-19 patients as an early warning signal of severe COVID-19 infection. Results showed that NLR could also be used as a prognostic factor. In the present study, the role of NLR in predicting chest X-ray (CXR) progression in hospitalized COVID-19 patients was investigated. Materials and Methods: The present study was an ambispective observational cohort study that included COVID-19 patients admitted to the isolation ward and COVID-19 intensive care unit between July and September 2021 in Buddhasothorn Hospital, Chachoengsao, Thailand. NLR and demographic findings were analyzed. Results: Medical details of 564 patients were retrospectively analyzed using 3.24 as the cut-off value of the maximum Youden index to classify a high NLR group and a low NLR group. The estimated cumulative hazard function for CXR progression in the high NLR group was statistically significant, (HR 1.31, 95% CI 1.02 to 1.68, p=0.031). Univariate analysis suggested that high NLR value and three or more clinical risk factors (age 60 years or older, diabetes mellitus, chronic obstructive pulmonary disease, chronic kidney disease, cirrhosis, stroke, obesity, and immunocompromised) were associated with CXR progression, while multivariate analysis determined high NLR as an independent predictive marker for COVID-19 CXR progression (aOR 1.54, 95% CI 1.06 to 2.23, p=0.022). Using NLR along with pre-existing comorbidity risk factors significantly increased the predictive value for COVID-19 CXR progression (area under the ROC curve 0.565, p=0.017). Conclusion: High NLR at the time of hospitalization was identified as a simple predictor for COVID-19 CXR progression requiring close monitoring. Keywords: Neutrophil-to-lymphocyte ratio (NLR); COVID-19; Disease progression; Predictive factor; Hospitalization