BACKGROUNDDetrusor overactivity (DO) is a known cause of lower urinary tract symptoms and occurs in 50% - 75% of benign prostate hyperplasia (BPH) patients. We sought to investigate the clinical and urodynamic factors that are associated with the presence of DO in Chinese BPH patients.

METHODSTwo hundred and eighty-seven consecutive patients with clinical BPH were retrospectively evaluated in this study. Each patient underwent urodynamic evaluation and completed the International Prostate Symptom Score (IPSS) and Quality of Life (QoL) questionnaire. Patients with neurological symptoms or other diseases likely to affect detrusor functions were strictly excluded. The 184 BPH patients included in the study were divided into groups according to the presence of DO as shown in urodynamic tests. Univariate analysis of factors associated with the presence of DO were performed using Student's t-test and the Mann-Whitney test; multivariate analysis used stepwise Logistic regressions. The relationship between degree of bladder outlet obstruction (BOO) and DO was also investigated using a linear-by-linear association test.

RESULTSOf 184 BPH patients, DO was present in 76 (41.3%). On univariate analysis, patients with DO were older (P = 0.000), and showed smaller maximal bladder capacity (MBC, P = 0.000) and voided volume (P = 0.000), higher maximal detrusor pressure (P = 0.000) and projected isovolumetric pressure (PIP) (P = 0.005), higher Abrams-Griffiths number (P = 0.000) and degree of bladder outlet obstruction (P = 0.000), higher IPSS (P = 0.000) and irritative IPSS subscores (P = 0.000). Stepwise Logistic regression analysis showed that PIP (OR = 1.012, 95% CI 1.002 - 1.023, P = 0.019), age (OR = 1.030, 95%CI 1.005 - 1.067, P = 0.059), and MBC (OR = 0.993, 95%CI 0.990 - 0.996, P = 0.000) were independent risk factors for DO in BPH patients. Linear-by-linear association tests indicated a positive linear association between DO and severity of BOO, with incidence of DO increasing with BOO grade (P = 0.000).

CONCLUSIONSIn Chinese BPH patients, PIP, MBC, and age were independent factors affecting the presence of DO. DO incidence continuously increases with the degree of BOO.