A Prediction Model of Detrusor Underactivity Based on Symptoms and Noninvasive Test Parameters in Men with Lower Urinary Tract Symptoms: An Analysis of a Large Group of Patients undergoing Pressure-Flow Studies

Purpose: We sought to identify the symptoms and noninvasive test parameters associated with detrusor underactivity and develop a prediction model of detrusor underactivity. We analyzed clinical data on male patients with lower urinary tract symptoms who underwent pressure-flow studies. Materials and Methods: Included in analysis were 909 men who met study criteria and whose data included the International Prostate Symptom Score, free uroflowmetry, post-void residual urine volume and prostate volume. Using these data we examined the significant symptoms and noninvasive test parameters associated with detrusor underactivity and developed a prediction model of detrusor underactivity. Results: Of the 909 patients 454 (50%) were classified with detrusor underactivity. On logistic regression analysis older patient age, smaller prostate volume, a lower urgency symptom score, a higher weak stream symptom score and a lower maximum flow rate were selected as independent predictors of detrusor underactivity. The prediction model of detrusor underactivity consisting of these 5 factors showed satisfactory performance (C statistic 0.724). Conclusions: We developed a prediction model of detrusor underactivity in male patients with nonneurogenic lower urinary tract symptoms. The model was based on 5 predictive factors, namely older age, smaller prostate volume, 2 symptoms (less urgency and a weak stream) and a lower maximum flow rate. The model helps estimate the probability of detrusor underactivity in clinical practice without an invasive pressure-flow study.