STATISTICAL ANALYSIS
The Generalized Estimating Equations method was used to evaluate the
association between the variables and pain or complications. The
estimates were calculated by maximum likelihood in order to avoid bias
on the difference in the number of PLB for each patient. Observations
within a given patient were not independent and intra-patient
correlation and variation were introduced into the analysis using a
mixed generalized linear model.
The Chi-square or Fisher’s exact tests were used to compare categorical
variables and the Mann-Whitney test for numerical variables. Statistical
analysis was performed using the SAS for Windows version 9.4 system. The
level of statistical significance adopted in the analysis was 5%.