Statistical analysis
Patient characteristics were presented and compared according to bladder
compliance using the mean ± standard deviation (SD) for continuous
variables and a frequency table for categorical variables. Preoperative
and postoperative data of I-PSS questionnaires and uroflowmetry with
post-voided residual urine were presented and compared according to
bladder compliance. In addition, the changes in these parameters were
demonstrated and compared. The percent changes in PSA level and prostate
volume were also calculated and demonstrated according to bladder
compliance. A multivariable linear
regression analysis was performed to determine the impacts of bladder
compliance on long-term functional changes after adjusting other
variables, including age, body mass index, prostate volume, surgical
methods, and I-PSS related variables. For multivariable analysis, a
backward elimination method was used for analysis. The impact of bladder
compliance in the HoLEP and PVP groups was separately assessed using
multivariable analysis for the differences in the effects of bladder
compliance on functional outcomes according to surgical methods. In
addition, to confirm the results of the current study after considering
the effects of time, repeat measured analysis of variance (ANOVA) was
performed. All statistical comparisons were performed using IBM SPSS
Statistics, Version 21 (IBM SPSS, Armonk, NY, USA). A p value of
less than 0.05 was considered statistically significant.