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.
All age groups Risk group Risk factor COVID-19