Prognostic value of C-reactive protein in patients with COVID-19

Xiaomin Luo; Wei Zhou; Xiaojie Yan; Tangxi Guo; Benchao Wang; Hongxia Xia; Lu Ye; Jun Xiong; Zongping Jiang; Yu Liu; Bicheng Zhang; Weize Yang

As one of the most distinctive acute phase reactants, CRP can increase rapidly after the onset of inflammation, cell damage or tissue injury. Pulmonary diseases with inflammatory features usually raise serum CRP level in response to inflammatory cytokines such as IL-6, IL-1 or TNF-α. 16, 17 Hence, markedly elevated serum CRP level in non-survivors or patients with severe/critical illness in this study indicated excessive inflammatory response, which was consistent with raised serum pro-inflammatory cytokines observed in COVID-19 patients. 18, 19 The roles of CRP in case of diseases may involve host defense and inflammation. In response to inflammatory onset, CRP binds to pathogens and promotes their elimination by phagocytic cells, functioning as the first line of innate host defense. Besides, CRP can exhibit anti-inflammatory effects by inhibiting neutrophils chemotaxis. 20 However, by up-regulating expression of adhesion molecules, and pro-inflammatory IL-1, IL-6, IL-8, and TNF-α, CRP can also exert pro-inflammatory effects. 21 Controversial results of serum CRP level were observed in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). 22, 23 The association between high serum CRP level and a favorable outcome was found in adult patients with ALI/ARDS. 22 In elderly patients with ALI, however, high serum CRP level correlated to higher mortality, 23 which is consistent to our findings in patients with COVID-19. Direct attacks from SARS-CoV-2 and organ damage caused by excessive inflammatory response might be responsible for . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Second, some patients with critical illness were not admitted to intensive care unit as they should be due to shortage of resources, which undoubtedly had a negative impact on the outcome of those patients. Third, patients were not recruited consecutively due to exclusion of some cases without serum CRP detection on admission, which might bring about selective bias. Fourth, serum CRP level correlates with the degree of inflammatory response, 24 therefore, changes in CRP over time might provide more information about disease prognosis. However, no continuous CRP values over time were included in this study since it was designed to explore the potential of admission CRP in outcome prediction.