Patient reported outcomes tools in an observational study of female stress urinary incontinence

AIMS: To determine which patient characteristics, incontinence and non-incontinence related, are associated with the symptom severity scores of the Urogenital Distress Inventory (UDI) and the International Consultation on Incontinence Questionnaire Urinary Incontinence (ICIQ-UI); and to determine the association of both patient characteristics and symptom severity scores with quality-of-life scores of the Incontinence Impact Questionnaire (IIQ) and the Incontinence-Quality of Life (I-QOL) questionnaire. METHODS: Women presenting with stress urinary incontinence (SUI) symptoms in primary and secondary care entered the Stress Urinary Incontinence Treatment Study (SUIT), an observational study evaluating the cost-effectiveness of duloxetine compared to other non-surgical treatments for SUI. At enrollment patients completed the UDI-6, the short form ICIQ-UI, the IIQ-7 and the I-QOL. Multivariate linear regressions were performed with the UDI-6, ICIQ-UI SF, IIQ-7, and I-QOL as outcomes. RESULTS: The total number of incontinence episodes is the most significant explanatory variable of the two symptom questionnaire scores, but the UDI-6 score also reflects the type of incontinence. The variability of the condition-specific quality-of-life questionnaires is primarily explained by the symptom severity questionnaire scores. Although there is a high intercorrelation, both these symptom questionnaires independently contributed significantly to the IIQ-7 and I-QOL total scores. CONCLUSIONS: The UDI-6 and ICIQ-UI SF can be regarded as scientifically sound symptom questionnaires in UI evaluation; but they have differences. Since the UDI-6 and ICIQ-UI SF independently contribute to the quality-of-life scores, this suggests that in incontinence research symptom questionnaires should not focus only on incontinence, but on a broader range of urogenital symptoms.