Incidence, clinical characteristics and prognostic factor of patients with COVID-19: a systematic review and meta-analysis

Xianxian Zhao, Bili Zhang, Pan Li, Chaoqun Ma, Jiawei Gu, Pan Hou, Zhifu Guo, Hong Wu, Yuan Bai. Incidence, clinical characteristics and prognostic factor of patients with COVID-19: a systematic review and meta-analysis. medRxiv 2020.03.17.20037572; doi:

Review written by:

Ignacio Hernandez-Morato, edited by Elizabeth Harty

Yellow - A pre-print meta-analysis of COVID-19 clinical research published until 02/25/2020.

Coronaviruses are a family of viruses that infect animals and humans. SARS-Cov-2 spreads more quickly than SARS-CoV-1 and MERS. Risk factors for COVID-19 are important to assess given the absence of a vaccine or specific treatment.

The authors included  30 studies for meta-analysis, with a  total of 53,000 COVID-19 confirmed patients, between December 2019 and February 19, 2020. Around 80% of the chosen studies were conducted in China. Just three studies were conducted in another country (one per each: USA, Australia and South Korea). The male to female ratio was 1.25 and average age was 49.8 years.

Epidemiology: Case severity rate (CSR) and case fatality rate (CFR) were slightly different in studies conducted within Wuhan compared to those conducted outside of Wuhan,  in  Wuhan higher (36.9% vs 10.9% of severe illness and 9.5% vs 0.2% of fatality rate). However, these differences were not significant. Onset to admission time was closely correlated with case severity rate and case fatality rate. CFR was higher in severe patients.The mean incubation period was 7.1 days with no difference between severe and non-severe cases.  The mean time from symptom onset to hospital admission was 6.18 days and longer in severe cases. Severe cases also presented older ages and were mostly men.

Clinical presentation: Fever (79.1%), cough (58%) and fatigue (29.3%) were the most common symptoms. The overall prevalence of comorbidities was 37.1%, with hypertension,diabetes and cardiovascular diseases the most frequent. These comorbidities were more common in severe cases.

Imaging: Radiological bilateral pulmonary abnormalities were observed in 87.2% of the cases.

Laboratory analysis: Severe cases presented  Higher levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), lactate dehydrogenase (LDH), D-dimer,  cardiac troponin I, and ferritin. Lymphocytes and platelet count were lower in these cases.

Risk factors for severity: Old age (>50 years old), male, smoking and comorbidities (chronic kidney disease, COPD, cerebrovascular diseases, tumor, diabetes and hypertension) were associated with poor prognosis.

Review Notes
  • The majority of studies were conducted in China. Knowing how COVID-19 presents differently in other contexts like the European Union and the United States is necessary to tailor infection prevention and management strategies.

  • The majority of the paper’s analysis has already been reported in a previous paper in the literature, specifically with regards to the risk factor groupings and comorbidities that are more frequent in severe COVID-19.

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