Objective: To assess the factors associated with the presence of idiopathic detrusor overactivity (IDO) in male patients with clinical benign prostatic hyperplasia (BPH). Materials and Methods: We prospectively evaluated 193 men who presented with lower urinary tract symptoms. Each patient underwent urodynamic evaluation, International Prostate Symptom Score (IPSS), uroflowmetry, residual volume check, and transrectal ultrasound for estimation of prostate volume. IDO was defined according to the new International Continence Society classification (2002) as involuntary detrusor contractions during cystometry, which may be spontaneous or provoked, regardless of amplitude. Patients were divided into groups according to the presence of detrusor overactivity and bladder outlet obstruction index (BOOI) greater than 40. Variables associated with the presence of IDO were analyzed using Student's t-test, chi-square test, linear-by-linear association test, and logistic regression analysis. Results: Of 193 patients, IDO was present in 49 (25.4%). BOOI and prostate volume showed significant but weak correlation. On univariate analysis, patients with IDO were older and showed smaller maximal bladder capacity (MBC), higher BOOI, higher maximal detrusor pressure at maximal flow rate, and higher irritative IPSS subscores. On logistic regression analysis, MBC and BOOI were the factors affecting the presence of IDO, with odds ratios of 0.981 and 1.046, respectively. Positive linear association was noted between BOOI and prevalence of DO by linear association test with prevalence of DO rising continuously with increasing BOOI. Conclusion: BOO is responsible for IDO and because the prevalence of IDO is inversely associated with the degree of obstruction, the treatment of BOO is potentially able to reverse the DO.
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