Results
Among 1608 patients, bladder compliance was < 12.5 mL/cm H2O in 50 patients (3.1%), and 12.5-25 mL/cm H2O in 232 patients (14.4%) (Table 1). Bladder compliance decreased as age increased (72.9 vs. 68.9 vs. 68.4 years, p<0.001) and body mass index decreased (22.9 vs. 23.6 vs. 24.1 kg/m2, p=0.002). The I-PSS total score (22.3 vs. 19.5 vs 19.0, p=0.018), storage sub-score (9.0 vs. 8.2 vs. 7.5, p=0.002), and quality of life (QoL) index (4.7 vs. 4.2 vs 4.1, p=0.001) increased as bladder compliance decreased, although the voiding sub-score was equivalent regardless of bladder compliance. PVP was more frequently performed in patients with decreased bladder compliance compared to HoLEP. At postoperative 6 months, the percent decrease in PSA (p=0.854) and prostate volume (p=0.755) were similar regardless of bladder compliance (supplementary table 1).
At postoperative 1, 12, and 36 months, I-PSS total, storage sub-score, and QoL index, respectively, were equivalent according to bladder compliance, although the preoperative values were significantly different (Supplementary table 2). In addition, the peak flow rate also showed no difference at postoperative 1, 12, and 36 months according to bladder compliance. However, BVE was significantly higher in men with bladder compliance >25 mL/cmH2O than decreased bladder compliance at postoperative 36 months, although there was no difference in BVE at postoperative 1 and 12 months. The 5-year serial follow-up data was demonstrated in Supplementary table 3. Decreases in I-PSS total score were significantly higher in patients with bladder compliance < 12.5 mL/cm H2O at postoperative 36 months (-14.3 vs. -8.5 vs. -7.4, p=0.019) (Table 2). Although decreases in voiding sub-score were equivalent regardless of bladder compliance, decreases in storage sub-score (-5.5 vs. -3.1 vs. -2.3, p=0.006) and QoL index (-2.8 vs. -2.1 vs. -1.7, p=0.031) at postoperative 36 months were significantly higher in patients with bladder compliance < 12.5 mL/cm H2O than in the other groups. However, there was no difference in total I-PSS score, voiding sub-score, and storage sub-score decreases according to bladder compliance at postoperative 1 and 12 months. Changes in the objective parameters, including peak flow rate and BVE, were equivalent during the postoperative follow-up duration of 36 months, except for the changes in BVE at postoperative 1 month.
On the multivariable analysis, bladder compliance < 12.5 mL/cmH2O (B=4.201, p=0.042), in addition to prostate volume, preoperative I-PSS total score, and surgical methods, was significantly associated with decreases in total I-PSS score at postoperative 36 months (Table 3). However, bladder compliance was not significantly associated with changes in voiding sub-score although bladder compliance < 12.5 mL/cmH2O (B=2.040, p=0.017) was significantly associated with storage sub-score after adjusting other variables. On
additional analysis, bladder compliance, regardless of the surgical methods, was associated with decreases in storage score, although statistical significance was not achieved in patients who underwent HoLEP (Table 4)
On the repeat measured ANOVA analysis, patients with bladder compliance < 12.5 mL/cmH2O showed significantly superior improvements in I-PSS storage score (vs. >25 mL/cmH2O; difference: -1.4, p=0.002, vs. 12.5-25 mL/cmH2O; difference: -1.3, p=0.023) and total score (vs. >25 mL/cmH2O; difference: -4.2, p=0.027, vs. 12.5-25 mL/cmH2O; difference: -4.9, p=0.026) compared to the other groups, although I-PSS voiding score was equivalent regardless of bladder compliance (Supplementary table 4).