Mixed urinary incontinence: A prospective study on the effect of trans-obturator mid-urethral sling.

OBJECTIVES: It is hypothesized that urethral dysfunction is central in mixed urinary incontinence (MUI) in women, since urine entering the proximal urethra under increased intra-abdominal pressure provokes a urethro-detrusorial reflex and involuntary detrusor contraction. Mid-urethral slings have been proposed as a solution. Our primary objective was to evaluate the long-term subjective and objective outcomes on continence and other urinary symptoms of a trans-obturator mid-urethral sling (TOT) procedure. Our secondary objectives were to determine its impact on quality of life (QoL), and to investigate which factors influence outcomes.

STUDY DESIGN: This is a single-centre prospective study on a consecutive series of 86 women who underwent TOT for MUI as defined by ICS/IUGA. Since the definition of MUI that we used is symptom-based, we included patients both with and without associated detrusor overactivity. All patients underwent placement of Monarc® Subfascial Hammocks.

STATISTICAL ANALYSIS: We used the McNemar chi-square test, the paired t-test and Fisher's exact test. A logistic regression model and odds ratios were used to assess age, parity, body mass index, menopausal status, preoperative detrusor over-activity, and detrusor pressure at maximum flow as possible factors for treatment failure. Only those that were statistically significant in the univariate analysis were included in the multivariate analysis.

RESULTS: With a mean follow-up of 59 months, SUI was cured objectively in 83.7% of patients and subjectively in 87.2%. Three patients underwent further anti-incontinence surgery. The continence rates were 74.4% for urgency urinary incontinence (UUI) and 66.3% for SUI-UUI. The patient-reported success rate was 87.2% ('much better' or 'very much better' on Patient Global Impression of Improvement scale). There were statistically significant improvements in all domains except general health. The univariate analysis found no significant risk factor for persistence of SUI. Median age >60 years and menopause were predictive for persistence of UUI. Median and mean age >60 years were predictive of persistence of overall incontinence. In the multivariate model, all variables lost their statistical significance.

CONCLUSION: Our study demonstrates TOT surgery can be performed for patients with MUI following unsuccessful conservative therapy. We also demonstrate that menopause and age >60 are risk factors for failure. This should be considered when counselling preoperatively.