Detrusor contraction power parameters (BCI and W max) rise with increasing bladder outlet obstruction grade in men with lower urinary tract symptoms: results from a urodynamic database analysis.

PURPOSE

To investigate to what extent detrusor work during voiding is influenced by bladder outlet obstruction (BOO) in adult men with lower urinary tract symptoms (LUTS).

MATERIALS AND METHODS

We reviewed data of patients with LUTS suggestive of benign prostatic hyperplasia who received computer-urodynamic investigations as part of their baseline clinical assessment. BOO was defined by the Schäfer classification and detrusor work during voiding was quantified by calculation of the bladder contractility index (BCI) and maximum Watt factor (W max) obtained by pressure-flow analysis.

RESULTS

A total of 786 men with medians of 64 years, IPSS 16 and prostate volume of 35 ml, were included in the study. A total of 462 patients (58.8 %) had BOO (Schäfer 2-6). Both detrusor contraction power parameters continuously increased with rising BOO grade. Median BCI increased from 73.3 in Schäfer 0 to 188.0 in Schäfer 6, whereas W max increased from 9.6 to 23.4 W/m(2) (p < 0.001). Results of BCI and W max correlated well (p < 0.001). With increasing BOO grade, there was a significant decrease of voiding efficiency (p < 0.001).

CONCLUSIONS

In adult male LUTS patients, detrusor contraction power parameters-BCI and W max-continuously increase with rising BOO grade. According to our results, it is impossible to determine a single threshold value for detrusor contraction power to diagnose detrusor underactivity in a group of LUTS patients with different BOO grades. The study is limited to men with non-neurogenic LUTS. Future studies should evaluate exact threshold values for BCI and W max in BOO subgroups to adequately define detrusor underactivity and investigate men with other bladder conditions.