The predictive values of various parameters in the diagnosis of stress urinary incontinence

The Maximum Urethral Closure Pressure (MUCP) and Functional Urethral Length (FUL) are significant parameters of the Urethral Pressure Profile (UPP), while the Q-tip angle and Bladder Neck Descent (BND) are the significant parameters of urethral hypermobility. We performed a study to evaluate the effects and predictive values of each of these parameters in the diagnosis of Stress Urinary Incontinence (SUI). A retrospective study was done involving 90 SUI patients and 38 non-SUI patients who underwent urodynamic study, Q-tip test and perineal ultrasound at Yonsei Medical Center between January, 1999 and February, 2002. There was no statistical difference between the SUI and non-SUI groups in terms of mean age, delivery history, menopausal age and body mass index. While the FUL and Q-tip angle showed significant differences (33.18 +/- 19.55 vs 33.12 +/- 13.37 mm, p=0.002; 65.94 +/- 21.69 vs 56.45 +/- 26.53 degrees C, p=0.02,respectively) neither the MUCP nor the BND showed any significant difference between the two groups (60.06 +/- 29.92 vs 48.97 +/- 42.95 cmH2O, p > 0.05; 1.09 +/- 0.75 vs 0.85 +/- 0.76 cm, p > 0.05; 0.71 +/- 0.80 vs 0.53 +/- 0.72 cm, p > 0.05). The odds ratios for the FUL and Q-tip angle were 1.038 (1.014, 1.061) and 1.017 (1.001, 1.033), respectively. The FUL and Q-tip angle had cut-off values of 1.36 cm (sensitivity: 68.8%, specificity : 54.1%, PPV : 73.8%, NPV : 48.1%) and 20.47 degrees C (sensitivity : 93.3%, specificity : 18.17%, PPV : 68.2%, NPV : 60%), respectively, in the diagnosis of SUI. The area under the curve (AUC) of the FUL and Q-tip angle were on average 0.625 (p=0.0016) and 0.575 (p=0.0012), respectively. Both the FUL and Q-tip angle showed a significant difference between SUI patients and the normal group. However, their value as a diagnostic tool was trivial, and since their sensitivity, specificity, positive predictive value and negative predictive value showed inconsistent results at each cut-off value, it would be difficult to apply them to clinical use. A further study is required to set-up standard diagnostic values of these variables for clinical use.