Reproducibility of pressure-flow variables in patients with symptomatic benign prostatic hyperplasia

To study the reproducibility of pressure-flow studies in patients with symptomatic benign prostatic hyperplasia and to investigate if the reproducibility is influenced by the method of intravesical pressure measurement, that is, transurethral catheterization versus suprapubic puncture.

The within-patient variation of maximum urinary flow rates and detrusor pressure at maximum flow was investigated in 25 patients in whom 2 (transurethral group) or 3 (suprapubic group) sequential voidings during urodynamic investigation were analyzed.

The within-patient variation of pressure-flow values was evaluated by the intraclass correlation coefficient, which was 0.71 for maximum urinary flow rate and 0.84 for detrusor pressure, suggesting a relatively high degree of reproducibility. However in 26% of the patients, the maximum flow rates changed by more than 3 mL/s or the detrusor pressure by more than 20 cm H2O during the repeated tests. There was no significant difference in the within-patient variation of pressure-flow values between the suprapubic group and the transurethral group.

In larger clinical trials where the assessment of treatment effects between groups is desired, a single pressure-flow test is sufficient. In the individual patient, a single pressure-flow curve is of limited value due to a considerable within-patient variation of the test and, for these patients, multiple consecutive tests are recommended for diagnosis of intravesical obstruction and assessment of individual patient's response to treatment.