Statistical analysis
Statistical significance was evaluated using c2-test,
Fisher exact test, and t-test. A multivariate logistic
regression was used to identify independent parameters
correlating with SSI. Receiver operating
characteristic (ROC) curve analysis, which is a graphical
plot of the sensitivity versus (1 specificity) for
a binary classifier system as its discrimination threshold
varies, was employed to obtain optimal cut-off
values for (i) BMI, (ii) estimated intraoperative blood
loss, and (iii) amount of fresh frozen plasma used.
Where appropriate, values were expressed as
mean SD. P< 0.05 by the two-tailed test was
considered statistically significant. All statistical
analyses were performed using statistical software
(SPSS for Windows, SPSS, Inc., Chicago, IL, USA).