Aims: Voiding dysfunction in adult men may be caused by bladder outlet obstruction (BOO) and/or detrusor underactivity (DU). Until now, it is only possible to classify BOO and DU by pressure-flow analysis. Low values of the maximum Watts factor (Wmax ) indicate DU but thresholds for the diagnosis have not been established. Purpose of this study was to construct a nomogram using bladder outlet resistance and detrusor contractility in order to classify BOO and DU simultaneously.
Methods: Treatment naïve men aged ≥40 years with uncomplicated lower urinary tract symptoms (LUTS) were prospectively evaluated. Patients were assessed with IPSS, prostate volume, uroflowmetry, post-void residual, and pressure-flow measurement. The bladder outlet obstruction index (BOOI) was used to determine BOO-grade and Wmax to calculate detrusor contractility. Individual BOOI-Wmax values were plotted in a graph. Linear interpolation was applied to determine the 10th, 25th, 50th, 75th, and 90th percentiles.
Results: Retrospective analysis of 822 male patients with means of 64 years, IPSS 16, and prostate volume of 40 cc. Patient and clinical parameters of the <25th percentile groups were significantly different compared to the 25th-50th percentiles: age (66 vs. 63 years, P = 0.006), bladder capacity (503 vs. 442 ml, P = 0.009), post-void residual urine (167 vs. 116 ml, P = 0.001), and voiding efficiency (67% vs. 73%, P = 0.015).
Conclusions: The nomogram quantifies the relationship between detrusor contractility and BOO in men with LUTS. A measurement value <25th percentile correlates with clinical indicators of DU and is proposed as a cut-off value for DU-diagnosis. Higher age, bladder capacity, and PVR as well as lower voiding efficiency indicate DU. Neurourol. Urodynam. 35:980-986, 2016. © 2015 Wiley Periodicals, Inc.
Keywords: benign prostatic hyperplasia; bladder outlet obstruction; detrusor underactivity; impaired bladder contractility; lower urinary tract symptoms.
© 2015 Wiley Periodicals, Inc.