Are Risk Factors for Failure after Mid-Urethral Sling Operation Different between Patients with Pure Stress and Those with Mixed Urinary Incontinence in the Short-Term Follow-Up?

ABSTRACT

PURPOSE: Although application of the mid-urethral sling (MUS) operation has expanded to more complicated cases such as patients with mixed urinary incontinence (MUI), the success rates in patients with MUI have been reported to be lower than those in patients with pure stress urinary incontinence (SUI). We evaluated and compared the risk factors for failure after MUS surgery in patients with pure SUI and in those with MUI. MATERIALS AND METHODS: Two hundred twenty-eight women were categorized as having pure SUI (Group A, 163 patients) or MUI (Group B, 65 patients). Preoperative evaluations including a symptom questionnaire, physical examination, and urodynamic study were performed. Patients underwent retropubic (17.5%) or trans-obturator (82.5%) MUS surgery. RESULTS: The demographic characteristics that differed between the 2 groups were body mass index, presence of cystocele, and severity of incontinence. The success rate in Group A (95.7%) was higher than that in Group B (84.6%) (p=0.015, chi-square test). In Group A, VLPP, PdetQmax, and weight of the 1-hour pad test were identified as risk factors for failure of the operation in the univariate analysis, but only weight of the 1-hour pad test was an independent risk factor in the multivariate analysis (adjusted odds ratio [OR]=3.5; 95% confidence interval [CI]=1.204-8.895, p=0.045). In Group B, menopause without hormone replacement, AUA Symptom Index-QoL score, maximal cystometric capacity (MCC), and involuntary detrusor contraction (IDC) were the risk factors in the univariate analysis, but only MCC (adjusted OR=0.9; 95% CI=0.645-0.984, p=0.032) and IDC (adjusted OR=2.3; 95% CI=1.014-3.309, p=0.044) were independent risk factors in the multivariate analysis. CONCLUSIONS: Unlike in pure SUI, weight of the 1-hour pad test was not a significant predictor of failure of surgery in MUI. Meanwhile, MCC and IDC, which indicate the pathophysiologic status of the detrusor muscle itself, were important predictors of failure of surgery in MUI.