Abstract Objective: To determine the ability of bladder wall thickness (BWT) in combination with non-invasive variables to distinguish patients with bladder outlet obstruction (BOO).
Patients and methods: Patients completed the International Prostate Symptom Score (IPSS) questionnaire and prostate size was measured by transrectal ultra- sonography (US). Pressure-flow studies were performed to determine the urody- namic diagnosis. BWT was measured at 250-mL bladder filling using transabdominal US. Recursive partition analysis (RPA) recursively partitions data for relating independent variable(s) to a dependent variable creating a tree of parti- tions. It finds a set of cuts of the dependent variable(s) that best predict the indepen- dent variable, by searching all possible cuts until the desired fit is reached. RPA was used to test the ability of the combined data of BWT, maximum urinary flow rate (Qmax), post-void residual urine volume (PVR), IPSS, and prostate size to predict BOO.
Results: In all, 72 patients were included in the final analysis. The median BWT, voided volumes, PVR, mean Qmax, and IPSS were significantly higher in patients who had an Abrams/Griffiths (A/G) number of >40 (55 patients) compared to those
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154 Farag et al.
MCC, maximum cystometric capacity; NPV, negative predic- tive value;
PPV, positive predic- tive value;
Pves, vesical pressure; PVR, post-void resi- dual urine volume; Qmax, maximum urin- ary flow rate
with an A/G number of 40 (17 patients). RPA revealed that the combination of BWT and Qmax gave a correct classification in 61 of the 72 patients (85%), with 92% sensitivity and 65% specificity, 87% positive predictive value, and 76% nega- tive predictive value (NPV) for BOO (area under the curve 0.85). The positive diag- nostic likelihood ratio of this reclassification fit was 2.6.
Conclusions: It was possible to combine BWT with Qmax to create a new algo- rithm that could be used as a screening tool for BOO in men with lower urinary tract symptoms.
! 2017 Production and hosting by Elsevier B.V. on behalf of Arab Association of Urology. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/)