[Applying bladder outlet obstruction number to predict bladder outlet obstruction of benign prostatic hyperplasia]

Applying bladder outlet obstruction number (BOON) to predict bladder outlet obstruction (BOO) of benign prostatic hyperplasia (BPH).

Seventy-six male who were suspected to suffer from BOO due to BPH with lower urinary tract symptoms were evaluated. The data included prostate volume (by transrectal prostate ultrasound), maximum urine flow rate (Qmax) and mean voided volume to calculate the BOON by simple algorithm: prostate volume (cm(3))-3 x Qmax (ml/s)-0.2 x mean voided volume (ml). Pressure-flow study was also performed on each patient to get AG number and Schäfer obstruction grade. Correlation between traditional parameters, BOON and AG number was calculated to evaluate the price of using BOON to predict BOO.

Parameters such as age, prostate volume, maximum urine flow rate, residual urine and BOON were used as independent and AG was used as dependent to calculated the multiple linear regression. Data expressed the entire regression equation's R = 0.542 (P = 0.000), and result showed BOON had the strongest relationship with AG (P = 0.000). Eighteen patients' BOON number were greater than -10, by AG number and Schäfer obstruction grade proving, all these patients were suffered from BOO, the sensitivity and the specificity of judging BOO by BOON were 31% and 100% respectively. While take BOON as -20, the sensitivity and the specificity were 42.4% and 88.2%, when take BOON as -30, the sensitivity and the specificity were 66.1% and 82.4%, respectively. Fifty-two persons' BOON were greater than -40, 46 patients suffered from BOO, the sensitivity and the specificity were 77.9% and 64.7%, the specificity and the opportunity of having BOO decreased significantly. The data showed that: taking BOON = -30 as critical point can predict BOO with higher sensitivity and specificity, greater BOON means greater possibility of BOO.

Using BOON which is deduced from prostate volume, maximum urine flow rate and mean voided volume, the point -30 as critical point, can predict the probability of BOO with higher sensitivity and specificity.