Statistical analysis
SAS 9.4 and Review Manager 5.3 software were used for analysis and data
presentation. Continuous variables were represented by median and
interquartile range (IQR). Classification variables were summarized as
counts and percentages in each category. The age, gender, number and
clinical signs of COVID-19 pneumonia patients were statistically
described. Cochran-mantel-Haenszel test (stratified chi-square test) was
used to compare the differences between severe and non-severe forms of
COVID-19 pneumonia. With odds ratio (OR) as the effect size we used
Mantel-Haenszel test with fixed or random effect for further
meta-analysis of the clinical signs, and presented using the forest map.
The study precision/bias was measured using the funnel plot.