key: cord-0800163-7ylnxtcq authors: Fang, Shilin; Wang, Haizhou; Lu, Li; Jia, Yifan; Xia, Zhongyuan title: Decreased complement C3 levels are associated with poor prognosis in patients with COVID-19: a retrospective cohort study date: 2020-10-05 journal: Int Immunopharmacol DOI: 10.1016/j.intimp.2020.107070 sha: f602a1404e3809308093d618ad1baca81a7f4796 doc_id: 800163 cord_uid: 7ylnxtcq OBJECTIVES: To describe the humoral immune feature of patients with coronavirus disease 2019 (COVID-19). METHODS: The levels of total immunoglobulins (IgG, IgM, IgA, and IgE), complement (C3, C4) results were retrospectively analyzed in COVID-19 patients. Univariable and multivariable logistic regression were performed to explore the risk factors associated with the in-hospital death. RESULT: A total of 236 patients were enrolled in this study, of which 169 were transferred to another institution or discharged (survival group) and 67 died in hospital (non-survival group). Compared with survivors, the levels of IgA and IgE in non-survivors increased significantly, and level of complement C3 decreased. Non-survivors also showed higher incidence of chest tightness, breath shortness and dyspnoea; higher levels of inflammatory indicators, leukocytes and neutrophils; and low levels of lymphocyte subsets. Multivariable regression showed increasing odds of in-hospital death associated with older age (HR: 1.099; 95%CI: 1.057-1.143; p < 0.0001), d-dimer greater (HR: 1.294; 95%CI: 1.138-1.473; p < 0.0001) and decreased complement C3 level (HR: 0.073; 95%CI: 0.007-0.722; p = 0.025) on admission. Finally, in survival COVID-19 patients whose humoral immunity was re-examined, C3 levels tended to increase, while in non-survivors it decreased. CONCLUSION: Low level of complement C3 may be an alert to the admitted COVID-19 patients with additional management. Inhibition of the complement pathway might be an effective therapeutic to COVID-19 patients. patients. Univariable and multivariable logistic regression were performed to 29 explore the risk factors associated with the in-hospital death. Table 1) . 155 156 Compared to survivors, non-survivors had a significant increase of IgA (p < 9 158 (Fig. 1a) . In the univariable analysis, IgA (HR: 1.701; 95% CI: 1.301-2.224; p < 159 0.0001) level was significantly associated with higher odds of in-hospital death, level changes tended to increase (Fig. 1b, c) ; and in the non-survivors, the C3 172 level changes tended to decrease (p = 0.012), while there was no difference in 173 IgA levels changes during observation before they died (p = 0.594) (Fig. 1d, e) . In this study, we observed that 63% of patients were older male with higher 304 We declared no competing interests. 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