Correlation analysis between disease severity and inflammation-related parameters in patients with COVID-19: a retrospective study

Abstract

Background: COVID-19 is highly contagious, and the crude mortality rate could reach 49% in critical patients. Inflammation concerns on disease progression. This study analyzed blood inflammation indicators among mild, severe and critical patients, helping to identify severe or critical patients early.

Methods: In this cross-sectional study, 100 patients were included and divided into mild, severe or critical groups according to disease condition. Correlation of peripheral blood inflammation-related indicators with disease criticality was analyzed. Cut-off values for critically ill patients were speculated through the ROC curve.

Results: Significantly, disease severity was associated with age (R = -0.564, P < 0.001), interleukin-2 receptor (IL2R) (R = -0.534, P < 0.001), interleukin-6 (IL-6) (R = -0.535, P < 0.001), interleukin-8 (IL-8) (R = -0.308, P < 0.001), interleukin-10 (IL-10) (R = -0.422, P < 0.001), tumor necrosis factor α (TNFα) (R = -0.322, P < 0.001), C-reactive protein (CRP) (R = -0.604, P < 0.001), ferroprotein (R = -0.508, P < 0.001), procalcitonin (R = -0.650, P < 0.001), white cell counts (WBC) (R = -0.54, P < 0.001), lymphocyte counts (LC) (R = 0.56, P < 0.001), neutrophil count (NC) (R = -0.585, P < 0.001) and eosinophil counts (EC) (R = 0.299, P < 0.001). With IL2R > 793.5 U/mL or CRP > 30.7 ng/mL, the progress of COVID-19 to critical stage should be closely observed and possibly prevented.

Conclusions: Inflammation is closely related to severity of COVID-19, and IL-6 and TNFα might be promising therapeutic targets.

Keywords: Blood cell count; COVID-19; Cytokine; Disease severity; Inflammation.

Conflict of interest statement

There was no conflict of interest between the authors.

Figures

Fig. 1

Comparison of age and cytokines among mild, severe and critical patients with COVID-19. a age; b IL2R; c distribution comparison of IL-6; d distribution comparison of IL-8; e distribution comparison of IL-10; f distribution comparison of TNFα. Many examination data about IL-6, IL-8, IL-10 and TNFα were below the lowest testing limit, different ranks were set according to data distribution and reference range, and data distribution among different group were compared (c-f). Data are presented as mean ± standard error or percentage of distribution range. IL2R, interleukin-2 receptor; IL6, interleukin-6; IL8, interleukin-8; IL10, interleukin-10; TNFα, tumor necrosis factor α.*P < 0.05; **P < 0.05; ***P < 0.001

Fig. 2

ROC curve of age and inflammatory parameters for critical illness of COVID-19. a age; b IL2R; c CRP; d ferroprotein; e WBC; f NC. IL2R, interleukin-2 receptor; CRP, C-reactive protein; WBC, white cell counts; NC, neutrophil count. AUC, 95% CI and P values are shown in the figure

Fig. 3

Comparison of inflammatory parametes among mild, severe and critical patients with COVID-19. a sqrt (CRP); b ferroprotein; c PCT; d ESR. CRP, C-reactive protein; PCT, procalcitonin; ESR, erythrocyte sedimentation rate. Data are presented as mean ± standard error or percentage. *P < 0.05; **P < 0.05; ***P < 0.001

Fig. 4

Comparison of blood cell counts among mild, severe and critical patients with COVID-19. Data are presented as mean ± standard error or percentage. a WBC; b NC; c sqrt (LC); d EC. WBC, white cell counts; NC, neutrophil count; LC, lymphocyte counts; EC, eosinophil counts. *P < 0.05; **P < 0.05; ***P < 0.001