Risk Factors for Mortality of COVID-19 Patient Based on Clinical Course: A Single Center Retrospective Case-Control Study

Abstract

Background: Epidemiological factors, clinical characteristics, and risk factors for the mortality of COVID-19 patients have been studied, but the role of complementary systems, possible inflammatory and immune response mechanisms, and detailed clinical courses are uncertain and require further study. Methods: In this single center, retrospective case-control study, we included all COVID-19 inpatients transferred or admitted to Wuhan Tongji Hospital from January 3 to March 30 2020 who had definite clinical outcomes (cured or deceased) with complete laboratory and radiological results. Clinical data were extracted from the electronic medical records, and compared between the cured and deceased patients. ROC curves were used to evaluate the prognostic value of the clinical parameters, and multivariable logistic regression analysis was performed to explore the risk factors for mortality. The correlation between the variables was evaluated by Spearman correlation analysis. Results: 208 patients were included in this study, 182 patients were cured and discharged, 26 patients died from COVID-2019. Most patients had comorbidities, with hypertension as the most common chronic disease (80; 38%). The most common symptoms at onset were fever (149; 72%), cough (137; 66%), and dyspnea (113; 54%). Elevated leucocytes, neutrophils, inflammatory biomarkers (CRP, ferritin, IL6, IL8, procalcitonin), PT, D-dimer, myocardial enzymes, BUN, decreased lymphocyte and subsets (T cells, CD4 T cells, CD8 T cells, NK cells, T cells + B cells + NK cells), and immunological factors (C3, C4) indicated poor outcome. PT, C3, and T cells were confirmed as independent prognostic factors for mortality by logistic regression models. IL6 and CPR were positively correlated with neutrophils, but negatively with lymphocytes and lymphocyte subsets except B cells. IL8 and ferritin were negatively related to T cells and CD4 T cells. Positive associations existed between C3 and T cells, CD4 T cells, and CD8 T cells, whereas there was no significant correlation between C4 and lymphocyte subsets. PT was found positively correlated with IL6, IL8, and CRP. Reverse correlations were explored between C3, C4, and PT, CK-MB, total bilirubin. Conclusions: T cells, C3, and PT were identified as independent prognostic factors for mortality. Decreased C3 and C4, dysregulation of lymphocyte subsets and cytokines may lead to death after SARS-CoV-2 infection.

Keywords: COVID-19; SARS-CoV-2; complement component 3; immune function; inflammatory factors; lymphocyte subsets; prognosis.

Figure 1

Study flow diagram.

Figure 2

Kaplan–Meier estimates on survival by (A) T cells count; (B) C3; (C) PT; (D) BUN (stratified according to best cut-off). T cell, T lymphocyte; C3, complement component 3; PT, Prothrombin time; BUN, Blood urea nitrogen.

Figure 3

Clinical courses of 2 typical hospitalized patients (A,B) with COVID-19 from illness onset.

Figure 4

Temporal changes in laboratory markers (A–I) in hospitalized patients since onset of COVID-19. T cell, T lymphocyte; B cell, B lymphocyte; NK cell, nature killer cell; IL6, Interleukin 6; CRP, C-reactive protein; C3, complement component 3; BUN, Blood urea nitrogen; hs-cTnI, High-sensitivity cardiac troponin I.