Effects of retrospective quality control on pressure-flow data with computer-based urodynamic systems from men with...

To evaluate the effects of retrospective quality control on pressure-flow data with computer-based urodynamic systems from men with benign prostatic hyperplasia (BPH).

A total of 582 traces of pressure-flow study from 181 men with BPH was included in the study. For each trace, maximum urinary flow rate (Q(max)) and detrusor pressure at Q(max) (p(det.Qmax)) were, respectively, read from manually smoothed and corrected uroflow and detrusor pressure curves from the computer print-outs. Obstruction coefficient, International Continence Society (ICS) and Schaefer nomograms were used to detect urethral resistance and to diagnose obstruction. The results obtained by manual reading were compared with those from computer-based systems.

After manual correction, Q(max) underwent a consistently significant decrease by 1.2 mL/s on average (P < 0.001), and had a change range of 0.5-10.4 mL/s. However, p(det.Qmax) underwent inconsistently intra-individual changes after correction. The obstruction coefficient increased significantly, by an average of 0.07 (P < 0.05). Using the ICS nomogram, the percentage of obstruction increased from 69.8% to 73.9%, and of the non-obstruction decreased from 8.8% to 5.3% (P < 0.05). There were 11% of traces that changed the classifications using the ICS nomogram, and 28.9% that changed the grades for the Schaefer nomogram.

Systematically significant differences in parameters from pressure-flow study between manual readings and computer recordings were demonstrated. Manual correction resulted in a consistently lower Q(max), a higher urethral resistance, and an aggravating obstruction. Manual readings can correct considerable false diagnoses for obstruction. Retrospective quality control of pressure-flow data with computer-based systems is necessary.