Sample size calculation
Using a 5% significance level, a
sample size of 64 for each group was calculated to ensure a power of
90% and to detect a difference of 1 day in postoperative LOS between
the two groups. Taking a 20% drop-out rate into account, we ultimately
determined 72 cases per arm of our study.
Intention-to-treat analysis was
conducted for all of the included patients after randomization. The
per-protocol analysis was also performed.
Statistical analysis
Quantitative data were described as
means ± 1 standard deviation or as
medians and interquartile ranges
(IQR), where appropriate. Normally distributed quantitative data were
analyzed using the Student’s t -test; otherwise we used a
Mann–Whitney U test. We presented qualitative data as numbers
(percentages) and analyzed them by χ2 test or Fisher’s
exact-probability test. Multivariate logistic regression analysis was
used to assess the effect of the full ERAS-program elements both on
primary and secondary outcomes. A two-sided P value <
.05 was considered to be statistically significant. All of the analyses
were performed using SPSS for
Windows version 16.0 (SPSS Inc., Chicago, IL, USA).