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.