key: cord-0690736-ogpp0dwy authors: Damar Çakırca, Tuba; Torun, Ayşe; Çakırca, Gökhan; Portakal, Reyhan Derya title: Role of NLR, PLR, ELR and CLR in differentiating COVID‐19 patients with and without pneumonia date: 2021-09-12 journal: Int J Clin Pract DOI: 10.1111/ijcp.14781 sha: 070d7122e71dd0afc1eff018f861e44e27b4d14e doc_id: 690736 cord_uid: ogpp0dwy OBJECTIVES: Neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), monocyte/lymphocyte ratio (MLR), eosinophil/lymphocyte ratio (ELR), and C‐reactive protein (CRP)/lymphocyte ratio (CLR) are well‐established inflammatory indices. This study aimed to examine whether NLR, PLR, MLR, ELR and CLR could differentiate coronavirus disease 2019 (COVID‐19) patients with pneumonia from those of without. METHODS: We retrospectively examined the laboratory parameters including CRP, D‐dimer, procalcitonin and complete blood count of 306 COVID‐19 patients (pneumonic = 152 and non‐pneumonic = 154). NLR, PLR, MLR, ELR and CLR values of each patient were calculated. The ability of these indices to distinguish COVID‐19 patients with and without pneumonia was determined by receiver operating characteristic (ROC) analysis. RESULTS: NLR, PLR and CLR values were higher while ELR value was lower in pneumonic COVID‐19 patients compared with patients with non‐pneumonic COVID‐19 infection. MLR value was similar in the two groups. NLR, PLR and CLR were positively correlated with CRP and procalcitonin. ELR was negatively correlated with CRP. The ROC analysis revealed that the optimal cut‐off value of CLR for discriminating COVID‐19 patients with pneumonia from those without pneumonia was 1.14 and the area under curve (AUC) for CLR was 0.731 (sensitivity = 81.5% and specificity = 55.6%), which was markedly higher than the AUCs of NLR (0.622), PLR (0.585) and ELR (0.613). However, no statistical differences were observed between AUC values of NLR, PLR and ELR (P > .05). CONCLUSION: Our findings showed that NLR, PLR, ELR and CLR indices can be used in differentiating COVID‐19 patients with or without pneumonia. Among them, the CLR index was the best predictor of pneumonia in COVID‐19 patients. available in all emergency departments. 5 Besides, inside the CT suites are high-risk areas for nosocomial COVID-19 transmission. 6 For this reason, there is need for fast, cheap and widely accessible biomarkers to simplify the diagnostic process and administer timely treatment of COVID-19 pneumonia. In recent studies, the neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), monocyte/lymphocyte ratio (MLR) and C-reactive protein (CRP)/lymphocyte ratio (CLR), which are novel inflammatory markers, have been considered as useful indicators for diagnosis and prognosis of various infectious diseases, including COVID-19 infection. [7] [8] [9] [10] [11] [12] Eosinophil/lymphocyte ratio (ELR) is another marker of inflammation and can be easily calculated by the ratio of eosinophil count to lymphocyte count. 13 However, the diagnostic values of these indices for COVID-19 patients with pneumo- nia have not yet been investigated. Herein, we aimed to investigate the utility of NLR, PLR, MLR, CLR and ELR to distinguish COVID-19 patients with pneumonia from those without pneumonia. In the correlation analysis of NLR, PLR, ELR and CLR indices with inflammatory biomarkers in the COVID-19 patients, a positive correlation was observed between NLR, PLR, CLR values and CRP and procalcitonin. ELR value was negatively correlated with CRP ( Table 2 ). The AUC, cut-off value, sensitivity and specificity of NLR, PLR, ELR and CLR are presented in Table 3 • COVID-19 can cause life-threatening pneumonia. • Hyperinflammation plays a crucial role in COVID-19 lung damage. • NLR, PLR, MLR, ELR and CLR are well-established inflammatory indices. • Early diagnosis and treatment are crucial to reduce mortality in COVID-19 patients with pneumonia. • NLR, PLR and CLR were higher and ELR was lower in pneumonic COVID-19 patients compared with nonpneumonic COVID-19 patients. • There was a positive correlation between NLR, PLR, CLR values and CRP and procalcitonin levels. ELR value was negatively correlated with CRP. • CLR was more efficient than NLR, PLR and ELR in differentiating COVID-19 patients with or without pneumonia. As far as we know, this is the first study that investigates the role of NLR, PLR, ELR and CLR indices as inflammatory biomarkers for differentiating COVID-19 patients with and without pneumonia; and their correlation with CRP and procalcitonin. This study demonstrated that pneumonic COVID-19 patients had significantly higher NLR, PLR and CLR values; and significantly lower ELR compared with the patients with non-pneumonic COVID-19 infection. There was a positive relationship between NLR, PLR, CLR and CRP and procalcitonin levels; and an inverse relationship between ELR and CRP levels. In addition, CLR was found to be more useful than other indices in identifying cases of COVID-19 pneumonia. An excessive and uncontrolled cytokine production plays an important role in the pathogenesis of COVID-19 pneumonia. 14 The major limitation of our study is that being conducted in a single center with retrospective design. Also, the time elapsed since the onset of symptoms, smoking habits and body mass index, which may affect laboratory indexes, could not be evaluated because of missing data. Pneumonic COVID-19 patients had significantly higher NLR, PLR and CLR; and significantly lower ELR compared with the nonpneumonic patients. There was a positive correlation between NLR, PLR, CLR and CRP and procalcitonin levels; and an inverse correlation between ELR and CRP levels. Besides, ROC analysis indicated that the AUC of CLR was significantly greater than the AUCs of NLR, PLR and ELR, and therefore the predictive capacity of CLR for COVID-19 pneumonia was better than the other three. Accordingly, CLR index could help clinicians to identify COVID-19 patients with pneumonia. An oral presentation was made at the 9th Turkey EKMUD Scientific Platform held online from May 20 to 23, 2021. The authors have declared no conflicts of interest. Ethics Committee Commission (Protocol number: HRU/20/15/09). 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