Mixed incontinence: the misclassification of patients and limitations of clinical trials

The management of mixed urinary incontinence in women

Mixed urinary incontinence is a common diagnosis among women with urinary leakage and is often present in women who are unable to characterize their incontinence. Research and optimized clinical treatment of these patients is limited by the challenges in objectively defining and stratifying this population. The evaluation of these patients should follow the same general principles as any assessment of any women with incontinence; however, it is essential to define whether urge or stress incontinence is the predominant symptom. Urodynamics (UDS) may be helpful in this regard and may help predict surgical outcomes. Behavioural therapy, weight loss, and pelvic floor muscle therapy are usually appropriate initial management strategies. In postmenopausal women, vaginal estrogen can be considered, and in women with equal parts stress and urge incontinence or urge-predominant mixed incontinence, a trial of anticholinergics or beta-3 agonists is appropriate. In women with stress-predominant or equal parts stress and urge incontinence, stress incontinence surgery can be considered, with the caveat that outcomes are generally worse among women with more severe levels of urgency, success rates may not be as durable, and a significant proportion of women may need additional medical therapy.

Mixed incontinence: comparing definitions in women having stress incontinence surgery

OBJECTIVE

To develop an empirically derived definition of mixed urinary incontinence (MUI) for use in incontinence outcomes research.

METHODS

Participants in a randomized trial comparing the fascial sling and. Burch colposuspension were assessed using standardized measures including the Medical, Epidemiologic and Social Aspects of Aging (MESA), UI questionnaire, the Urogenital Distress Inventory (UDI), 3-day urinary diary and urodynamic studies (UDS). Participants were required to have stress incontinence with a MESA stress subscale score > MESA urge subscale score. Several definitions of MUI were considered. Logistic and linear regression analysis methods were used to predict clinical outcomes based on the different MUI definitions. Analyses were carried out using SAS (SAS Institute, Inc., Cary, NC, Version 9.1). Statistical significance was defined at P-value <0.05.

RESULTS

In 655 participants, the proportion of women with MUI varied from 8.3% to 93.3% depending on the MUI definition All definitions were associated with severity as measured by the frequency of incontinence episodes at baseline; however little of the variability was explained by any single definition. No strict cut-off value for these baseline measures was identified to predict clinical outcomes.

CONCLUSIONS

These MUI definitions do not adequately categorize clinically relevant UI subgroups. For research reporting, MUI subcomponents of stress and urge UI should be described separately rather than as a single dimension.