Prediction of Bladder Outlet Obstruction in Male Patients with Lower Urinary Tract Symptoms Based on Symptom Scores and Noninvasive Office-Based Diagnostic Tools

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Purpose: The purpose of this study was to investigate the predictive values of combining symptom scores, prostatic parameters, uroflowmetry parameters, intravesical prostatic protrusion, and prostatic urethral angle for the establishment of a bladder outlet obstruction (BOO) risk score for diagnosing BOO in men with lower urinary tract symptoms. Materials and Methods: A total of 355 men with lower urinary tract symptoms were enrolled and divided into a training set (N = 285) and validation set (N = 70). Videourodynamic studies were used to diagnose lower urinary tract dysfunction subtypes, which were subdivided into a non-BOO and BOO group, which included bladder neck dysfunction and benign prostate obstruction. The parameters were categorized as 0, 1, 2, or 3 according to their cutoff value regarding the specificity of predicting BOO. The BOO risk score was constructed by summing scores of seven variables of symptoms and prostate and uroflowmetry parameters. The area under the curve (AUC) was used to select appropriate cutoff values for predicting lower urinary tract dysfunctions. Results: Among the 355 men examined, 234 (65.9%) had BOO, including 136 (38.3%) with bladder neck dysfunction and 98 (27.6%) with benign prostate obstruction. Other lower urinary tract dysfunctions included detrusor overactivity in 37 patients (10.4%), dysfunctional voiding in 28 patients (7.9%), poor relaxation of the external sphincter in 26 patients (7.3%), detrusor underactivity in 14 patients (3.9%), stable bladder in 9 patients (2.5%), and a hypersensitive bladder in 7 patients (2%). With the summation of the BOO risk scores from each variable, a BOO risk score of ≥10 could yield a sensitivity of 0.822 and specificity of 0.656 for benign prostate obstruction in the training set [AUC = 0.800 (0.741–0.859)] and a sensitivity of 0.80 and specificity of 0.64 in the validation set [AUC = 0.813 (0.701–0.925)]. Conclusions: With office-based diagnostic tools, including symptom scores and uroflowmetry and prostate parameters, a BOO risk score was established. A BOO risk score of ≥10 can predict the presence of benign prostate obstruction in >80% of men with lower urinary tract symptoms refractory to initial medication.