Comparison of Free Uroflowmetry and Pressure-Flow Study Parameters: A Retrospective Analysis in Non-Neurogenic Male Patients.

PURPOSE: Urodynamic evaluation requires transurethral catheterization that may introduce measurement artifacts affecting diagnostic accuracy. While catheter effects have been reported in female populations, systematic assessment of flow parameter differences between free uroflowmetry and pressure-flow studies in male patients remains limited. This study aimed to quantify these parameter differences in men with lower urinary tract symptoms.

METHODS

This retrospective observational study examined non-neurogenic 83 male patients who underwent both free uroflowmetry and urodynamic evaluation between January 2021 and December 2024. Patients were stratified into two groups based on maximum flow rate comparisons: Group 1 (free uroflowmetry Qmax > pressure-flow study Qmax) and Group 2 (free uroflowmetry Qmax ≤ pressure-flow study Qmax). ROC analysis evaluated discriminative performance of uroflowmetry parameters, with Youden Index determining optimal cut-off values. Statistical analyses included paired t-tests, independent samples t-tests, and logistic regression.

RESULTS

Group 1 comprised 72 patients (86.7%) demonstrating significant flow reduction during urodynamics, while Group 2 included 11 patients (13.3%). Mean maximum flow rate was significantly reduced during pressure-flow studies (12.72 ± 5.71 versus 7.64 ± 6.49 mL/s, p < 0.001), representing a 5.08 mL/s mean reduction. ROC analysis revealed moderate discriminative ability for maximum flow rate (AUC: 0.730, 95% CI: 0.585-0.875, p = 0.014) and mean flow rate (AUC: 0.720, 95% CI: 0.572-0.868, p = 0.019). Optimal cut-off values were 11.55 mL/s for maximum flow rate (sensitivity: 58.3%, specificity: 81.8%) and 6.15 mL/s for mean flow rate (sensitivity: 56.9%, specificity: 81.8%).

CONCLUSIONS

Flow parameter differences between free uroflowmetry and pressure-flow studies are prevalent in 86.7% of male patients, with clinically significant reductions averaging 5.08 mL/s. These findings highlight the need for standardized protocols accounting for measurement artifacts in urodynamic interpretation and emphasize the importance of baseline uroflowmetry parameters in predicting catheter-related effects.

CLINICAL TRIAL REGISTRATION: This study was not a clinical trial and therefore did not require registration.