The clinical implication of dynamic neutrophil to lymphocyte ratio and D-dimer in COVID-19: A retrospective study in Suzhou China

Abstract

Objective: To investigate the clinical features of COVID-19 cases in Suzhou China. Biomarkers were screened out of hematological parameters for risk stratification.

Method: Confirmed COVID-19 adult patients in Suzhou were included. The patient data was collected, and the results of laboratory examinations were compared between the mild/moderate and severe COVID-19 groups. A ROC was calculated to compare the diagnostic performance of candidate indexes, and dynamic levels of hematological indexes were compared between the two groups.

Result: 75 patients were enrolled, with a mean age of 46.6 ± 14 years, and 45 patients were male. All patients were classified into two groups: the mild/moderate group and the severe group. WBC, neutrophil to lymphocyte ratio (NLR), D-dimer, and fibrinogen levels of the severe group were significantly higher (P < 0.05) than the mild/moderate, and the lymphocyte was lower. The ROC test showed that the hematological parameters had a larger AUC than that of inflammatory factors. There was a significant difference in lymphocyte and fibrinogen levels between the two groups on day 1 (P < 0.05). However, NLR of the severe group was higher than the mild/moderate on days 1, 4 and 14 (P < 0.01), and so was D-dimer on days 1, 7 and 14 (P < 0.05).

Conclusion: The common COVID-19 abnormal hematological indexes on admission included hyperfibrinogenemia, lymphopenia, the elevation of D-dimer, and leukopenia, which were significantly different between the mild/moderate and severe COVID-19 groups. Furthermore, the dynamic change of NLR and D-dimer level can distinguish severe COVID-19 cases from the mild/moderate.

Keywords: Coronavirus disease 2019; D-dimer; Neutrophil to lymphocyte ratio.

Fig. 1

The computed tomography of two COVID-19 patients. Case 1. A 41-year-old man who had traveled to Wuhan. On January 29 he visited a fever clinic in Suzhou because of mild fever and dry cough. The RT-PCR nucleic acid for SARS-CoV-2 turned out positive and he was admitted to our center. Chest CT 1A, 1B, 1C showed multiple ground-glass opacity with mild progression of infiltrations on day 1, day 7 and day14. Case 2. A 70-year-old man who was admitted to our ICU and received HFNC and NIV support. Chest CT showed lung lesions were multiple patchy ground glass shadows (2D), but on day 7 the lung infiltrations became diffuse and focal consolidation emerged (2E) and on day 14 mild absorption of lung lesions on CT can be seen (2F). His symptoms improved obviously and discharge on March 10.

Fig. 2

The receiver operation curve of inflammatory indexes and hematological parameters for disease severity classification of COVID-19. A. ROC analysis of C-reactive protein and procalcitonin for discriminating 16 severe COVID-19 cases from 59 mild/moderate cases. B. ROC analysis of peripheral hematological parameters (lymphocyte, NLR, fibrinogen and D-dimer) analysis for discriminating 16 severe cases from 59 mild/moderate cases.

Fig. 3

Dynamic change of peripheral blood cell indexes and coagulation factors between severe and mild/moderate patient group. A. Lymphocyte level on four different days (1, 4, 7, 14) between the mild/moderate and severe patient group. B. Neutrophil-to-lymphocyte ratio (NLR) on four different days (1, 4, 7, 14) between the mild/moderate and severe patient group. C. Fibrinogen level on three different days (1, 7, 14) between the mild/moderate and severe patient group. D. D-dimer level on three different days (1, 7, 14) between the mild/moderate and severe patient group.