Statistical analysis
SPSS 22.0 software (SPSS Inc., Chicago, IL, USA) was used for all
statistical analyses. Data are presented as the means ± SD or
percentages as appropriate. A paired t -test was used to analyze
preoperative and postoperative data. Continuous data are presented as
medians and ranges, and categorical data are presented as frequencies
and percentages. The hospitalization length and hospitalization cost
were analyzed using the Mann-Whitney U test. Categorical variables were
analyzed using the chi-squared test or Fisher’s exact test when the
number of variables was less than five. P -values <0.05
were considered to be statistically significant.