Statistical analysis
Despite the comparison of analgesic effects of different concentrations
of ropivacaine under a single shot of SAPB[13].
However, no previous studies have tested the analgesic effect of
different concentrations of ropivacaine in continuous SAPB. The sample
size was determined according to the primary outcome using Power
Analysis and Sample Size (PASS) 15. Following previous reports, we set
the VAS non-inferiority margin at 1.3 as an acceptable difference in
this study, and the standard deviation is anticipated to be 2.0 cm[15-17], assuming a one-sided type I primary error
rate of 2.5% and 80% power. Group L: Group H=1:1, and a minimum sample
size of 39 patients for each group was estimated. Considering a 10%
rate of potential dropout, a total of 44 patients for each group were
finally included.
Data were analyzed using Statistical Package for Social Sciences (SPSS)
26.0 for Windows (SPSS Inc., Chicago Illinois, USA). Descriptive data
are shown as the mean (with standard deviation) depending on the (normal
or skewed) distribution of data, and categorical data are shown as
percentages. Comparisons of categorical data were performed with the
chi-square test, and an independent t test was used for numerical data
comparisons. All statistical tests were two-sided tests, and p values
<0.05 were considered significant.