The Predictive Role of Neutrophil to Lymphocyte Ratio and Platelet to Lymphocyte Ratio on Intensive Care Unit Admission and Mortality of COVID-19 Patients in Iran

Abstract

Since the outbreak of COVID-19 several studies conducted to identify predictive factors which are associated with prognosis of COVID-19. In this study we aimed to determine whether the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) could help the clinicians to predict intensive care unit (ICU) admission and mortality of COVID-19 patients. This retrospective cohort study involved examining the medical records of 311 Iranian COVID-19 patients from 22 July 2020 to 22 August 2020. All characteristic data and laboratory results were recorded. The receiver operating characteristic (ROC) curve was used to identify the predictive value of studied parameters for ICU admission and death. Comparison of data revealed that some factors were jointly higher in non-survivors and ICU admitted patients than survivors and non-ICU admitted patients, such as: age, hemoglobin (HB), NLR, derived neutrophil-to-lymphocyte ratio (dNLR), PLR, systemic inflammatory index (SII), lactate dehydrogenase (LDH), Respiratory diseases, ischemic heart disease (IHD). Multivariate logistic regression analysis showed that only hypertension (OR 3.18, P=0.02) is an independent risk factor of death in COVID-19 patients, and also PLR (OR 1.02, P=0.05), hypertension (OR 4.00, P=0.002) and IHD (OR 5.15, P=0.008) were independent risk factor of ICU admission in COVID-19 patients. This study revealed that the NLR, PLR, platelet-to-white blood Cell ratio (PWR), dNLR and SII are valuable factors for predicting ICU admission and mortality of COVID-19 patients.

Role of Neutrophil-Lymphocyte Ratio in Predicting Severity of COVID-19

“…21 28-days hospital mortality was found to be significantly associated with high NLR (≥3.42), which was also comparable to previous studies. 11,12,15,[22][23][24] In line with research findings, Yang et al observed that NLR>3.3 was associated with lower survival compared with NLR <3.3 (NLR >3.3: 6.3 days and NLR <3.3: 13.5 days). 12 In a prospective clinical study on 195 elderly subjects with acute pulmonary infection, Cataudella et al reported that NLR was an excellent predictor of mortality at 30 days, along with a correlation between the level of NLR and mortality.…”

“…14 Besides, Foroughi et al reported that the optimal cut-off value for NLR was 6.22 to significantly predict the ICU admission in patients with COVID-19 with 81% sensitivity. 15 Several other studies also found significant cut-off value for NLR to predict severe COVID-19. 3,[16][17][18] Furthermore, in a meta-analysis, Henry et al observed that patients with severe COVID-19 disease present with increased leucocytosis, neutrophilia, lymphopenia, and thrombocytopenia than those with non-severe disease.…”