Statistical analysis
Descriptive statistics were calculated for the patients’ characteristics
and SBE parameters, and are presented as medians, means, and ranges.
Continuous variables were expressed as mean (standard deviation) or
median (range). Categorical variables were presented as numbers and
percentages or rates. Differences in numerical variables were analyzed
by the Student’s t-test, or the Mann-Whitney U test. While differences
in categorical variables were analyzed by the χ2 test,
or Fisher’s exact test. A two-sided P value of less than 0.05 was
considered statistically significant. All the statistical analyses were
performed using SPSS 21.0 (IBM, Armonk, USA).