Statistical analysis
The statistical analysis was performed using GraphPad Prism 6.
Categorical variables are reported as frequencies and percentages.
Continuous variables are reported as mean ± standard deviation (SD).
Categorical variables were compared using Chi square test. For
comparison between severe and critically severe patients, the
Mann-Whitney U test was used. One-way ANOVA followed by Tukey’s test was
used for statistical comparisons between healthy subjects, severe and
critically severe group.