Urodynamic characteristics of different types of detrusor overactivity in patients with benign prostatic obstruction

This study aimed to investigate whether the presence or the absence of detrusor overactivity (DO) in patients with urodynamic-confirmed benign prostatic obstruction (BPO) leads to alterations in urodynamic parameters.

This study is a retrospective analysis of patients with urodynamic-confirmed BPO [Bladder Outlet Obstruction Index (BOOI) >40]. Patients with a clinical diagnosis of benign prostatic hyperplasia (BPH) or benign prostatic enlargement (BPE) were initially screened, but only those with BOOI > 40 were included. Based on the presence or absence of DO during urodynamics, patients were categorized into two groups: BPO with DO and BPO without DO. Subsequently, the BPO with DO group was further stratified according to DO subtype into BPO with terminal DO (TDO) and BPO with phasic DO (PDO). Differences in the urodynamic parameters and the DO-related indices among these groups were then evaluated. In addition, correlations between the DO-related indicators and the urodynamic parameters within each DO subtype were further examined.

There were 75 patients assigned to the BPO with DO group and 71 to the BPO without DO group. There was a statistically significant difference in the maximum cystometric capacity (MCC) and bladder compliance (BC) between the BPO with DO group and the BPO without DO group: 259.05 ± 44.54 vs. 273.13 ± 36.69 (p = 0.04) and 158.71 ± 83.86 vs. 210.95 ± 82.58 (p < 0.001), respectively. The BPO with PDO group comprised 38 patients, while the BPO with TDO cohort included 37 patients. There exists a statistically significant difference between MCC and BC: 291.50 (248.75-301.75) vs. 250.00 (210.00-296.00) (p = 0.02) and 184.00 (150.50-286.75) vs. 103.00 (85.00-141.50) (p < 0.001), respectively. Univariate regression analysis revealed a statistically significant negative correlation between the maximum contraction amplitude of DO and BC exclusively within the BPO with TDO cohort (r _s = -0.34, p = 0.03). Multivariable analysis confirmed this independent correlation (β = -0.33, 95%CI = -0.59 to -0.07, p < 0.05). Age was identified as an independent risk factor for DO (OR = 1.19, p < 0.001) and first desire to void (FD) as an independent protective factor (OR = 0.98, p < 0.001).

This preliminary study indicates that DO is associated with storage-phase urodynamic alterations in BPO patients, with no notable association with the voiding phase parameters. Multivariable analysis identified age as an independent risk factor for DO and FD as an independent protective factor. TDO is associated with more pronounced storage-phase changes than PDO. In the TDO subgroup, the correlation between BC and DO contraction amplitude was independent of age. However, several other comparisons remain unadjusted; therefore, these findings are exploratory. Future prospective studies with larger samples and age-adjusted designs are needed.