Statistical analysis
The data were presented as the mean ± standard deviation (SD) for
continuous variables or as number and percentages (%) for categorical
variables. For continuous and categorical variables, differences between
the two groups were compared using the Student’s t -test,
Mann–Whitney U test, and Fisher’s exact test, respectively. All tests
were two sided and a P value of <0.05 was considered
statistically significant. All statistical analyses were conducted using
SPSS version 21.0 (IBM Corp., Armonk, NY, USA).