Statistical Analysis
Continuous study data were presented as the mean ± Standard deviation.
Categorical variables were presented as the number and percentage. To
compare the severity of each symptom between the groups with respect to
continuous variables was tested with Student’s t-test or Mann-Whitney U
test, with the former being used for normally distributed variables and
the latter for non-normally distribute dones. The difference with
regard to categorical variables was tested using the chi-squared test.
To determine potential risk factors for preoperative mortality,
multivariable logistic regression analysis was performed. All
statistical analyses were performed using SPSS package for Windows
version 21 (SPSS Inc., Chicago, IL, USA). For all statistical analyses,
p-value of <0.05 was considered statistically significant.