BACKGROUND: New evidence from retrospective cohort studies on risk of death from COVID-19 infection became available . We aimed to systematically review the clinical risk factors for fatal outcome of COVID-19 .

METHODS: We performed meta-analysis, using PubMed, EMBASE and Cochrane databases from December 1 2019 to June 10 2020 . The meta-analysis summarized clinical, laboratory, radiological features, and complications of non-survivors with confirmed COVID-19 . In addition, a fixed- or random-effects model was adopted based on the heterogeneity among studies . We also used funnel-plot with Egger's tests to screen potential publication bias .

RESULTS: In total, twenty studies with 15,408 COVID-19 cases were included in our meta-analysis . Male, current smoking, and older age were associated with in-hospital death . Patients aged 60 years or over had the highest pooled ORs [OR 4.94 (2.89 , 8.44) ]. Non-survivors were more likely to have diabetes, hypertension, cardiovascular disease (CVD), respiratory disease, or chronic kidney disease (CKD). Respiratory disease had the highest pooled ORs [OR 2.55 (2.14 , 3.05) ]. Dyspnea [OR 3.31 (1.78 , 6.16); I2 : 83 %] and fatigue [OR 1.36 (1.07 , 1.73); I2 : 0 %] were associated with increased risk of death . Increased white blood cell count, decreased lymphocyte and platelet counts, were also associated with increased risk of death . Biomarkers of coagulation function, inflammation, liver and kidney function, cardiac and muscle injury were also elevated in nonsurvivors .

CONCLUSIONS: Male, current smoking patients aged 60 years or over might face a greater risk of in-hospital death and the comorbidities such as diabetes, hypertension, CVD, respiratory disease, and CKD could also influence the prognosis of the COVID-19 . Clinical feature such as dyspnea and fatigue could imply the exacerbation and even death . Our findings highlighted early markers of mortality which were beneficial to identify fatal COVID-19.