Statistical analysis
The
repositive
rate of SARS-CoV-2 was estimated by dividing the number of
positive retest patients by the
number of COVID-19 patients. Categorical variables are described as
absolute numbers and percentages (%). Skewed and normally distributed
continuous variables are described as the median (interquartile range
[IQR] or range) and mean (standard deviation [SD]),
respectively. Chi-square tests and t-tests were used to compare
characteristics between positive retest patients and negative retest
patients.
Univariate
and multivariable logistic regression models(Tripepi, Jager, Dekker, &
Zoccali, 2008) were performed to estimate odds ratios (ORs) and 95%
confidence intervals (95% CIs) for associations of potential risk
factors with retested positivity.
Age (0-17, 18-44, 45-59, or ≥60
years), sex (male or female), continent (Asia, Africa or others),
severity (asymptomatic, mild, moderate, or severe) and clinical symptoms
(fever, dry cough, expectoration, myalgia, diarrhea or shortness of
breath) at the first admission were included in the multivariable model.
Analyses were all performed with SAS software (version 9.4 for Windows,
SAS Institute, Inc., Cary, NC, USA). Statistical tests were two-sided,
and P values of less than 0.05 were considered to indicate
statistical significance.