Objectives: To identify clinical characteristics of severe patients with COVID-19 .
Methods: The WHO database of publications on COVID-19 and PubMed were searched from inception to March 20 , 2020 and all valuable studies were analyzed using Stata 15.0 .
Results: We selected forty-four studies with 13,497 patients . In the comparison of severe and non-severe groups, age over 50 (OR = 4.090; 95% CI = 2.422–6.907, P = 0.000) and underlying disease (OR = 3.992; 95% CI = 2.631–6.507, P = 0.000) are risk factors . Female gender (OR = 0.740; 95% CI = 0.622–0.881, P = 0.001) is a protective factor . Characteristics like dyspnea (OR = 4.914; 95% CI = 3.069–7.867, P = 0.000), lymphopenia (OR = 5.528; 95% CI = 3.484–8.772, P = 0.000), thrombocytopenia (OR = 3.623; 95% CI = 1.034–12.691, P = 0.044), elevated C-reactive protein (OR = 5.217; 95% CI = 2.459–11.070, P = 0.000) and D-dimer (OR = 3.780; 95% CI = 1.481–9.648, P = 0.005) were more frequently in severe cases . Diffuse lesions and consolidation (OR = 4.680; 95% CI = 3.183–6.881, P = 0.000) in imaging was considered reliable .
Conclusions: Men older than 50 with underlying disease are susceptible to develop severe pneumonia while female gender is protective . The typical symptom of severe pneumonia was dyspnea, but high fever, headache and diarrhea were not significantly different among patients with varying degrees of severity . Lymphopenia, thrombocytopenia, elevated C-reactive protein and D-dimer occurred more frequently in severe patients and yet leukopenia is not a characteristic laboratory indicator . Diffuse lesions and consolidation are important imaging features to distinguish severe pneumonia.