Psychometric Properties and Practicability of the Self-Report Urinary Incontinence Questionnaire in Patients With Pelvic-Floor Dysfunction Seeking Outpatient Rehabilitation

Abstract

Pelvic-floor dysfunction (PFD) affects a substantial proportion of individuals, mostly women. In responding to the demands in measuring PFD outcomes in outpatient rehabilitation, the Urinary Incontinence Questionnaire (UIQ) was developed by FOTO in collaboration with an experienced physical therapist who has a specialty in treating patients with PFD. The purpose of this study was to evaluate psychometric properties and practicability of the 21-item UIQ in patients seeking outpatient physical therapy services due to PFD. This was a retrospective analysis of cross-sectional data from 1,628 patients (mean age=53 years, SD=16, range=18-91) being treated for their PFD in 91 outpatient physical therapy clinics in 24 states (United States). Using a 2-parameter logistic item response theory (IRT) procedure and the graded response model, the UIQ was assessed for unidimensionality and local independence, differential item functioning (DIF), discriminating ability, item hierarchical structure, and test precision. Four items were dropped to improve unidimensionality and discriminating ability. Remaining UIQ items met IRT assumptions of unidimensionality and local independence. One item was adjusted for DIF by age group. Item difficulties were suitable for patients with PFD with no ceiling or floor effect. Item difficulty parameters ranged from -2.20 to 0.39 logits. Endorsed items representing highest difficulty levels were related to control urine flow, impact of leaking urine on life, and confidence to control the urine leakage problem. Item discrimination parameters ranged from 0.48 to 1.18. Items with higher discriminating abilities were those related to impact on life of leaking urine, confidence to control the urine leakage problem, and the number of protective garments for urine leakage. Because this study was a secondary analysis of prospectively collected data, missing data might have influenced our results. Preliminary analyses supported sound psychometric properties of the UIQ items and their initial use for patients with PFD in outpatient physical therapy services.