Statistical analysis
Categorical data were compared with the χ2 or Fisher’s exact test, as
appropriate, and results are
reported as absolute and relative frequencies.
Quantitative
variables with a normal
distribution were compared witht tests and results are reported as the mean and standard
deviation (SD), while variables with a skewed distribution were compared
with the nonparametric Mann-Whitney U test and results are
expressed as the median and interquartile range (IQR). The threshold for
significance was set at P <0.05 (all tests 2-tailed).
All analyses were performed with GraphPad Prism v8 (GraphPad Software,
San Diego, CA).