Psychometric Validation and Scale Derivation of the ICIQ-Underactive Bladder Patient Reported Outcome Measure

Abstract

Aims: To complete the psychometric validation and scale derivation of the International Consultation on Incontinence Questionnaire-Underactive Bladder (ICIQ-UAB). Methods: The developmental ICIQ-UAB was administered within a Phase II randomised controlled trial of a drug for the treatment of underactive bladder at baseline and follow-up 4 weeks after the start of trial medication treatment. Descriptive analyses and exploratory factor analyses (EFAs) informed the derivation of scored domains for symptoms, health-related quality of life (HRQoL), and associated bother items. The reliability was assessed by Cronbach's α, while validity was assessed via the correlation with other concurrently administered PROMs at baseline. Responsiveness was evaluated using the change in mean scores from baseline to follow-up. Results: A total of 132 male and female patients with the symptomatic and urodynamic characteristics of detrusor underactivity were enrolled in the analysis. Descriptive analyses and EFAs informed scored domains for 11 symptom items with associated bother, and 7 HRQoL items with associated bother. A further 8 unscored symptom items and one overall HRQL item were retained for their clinical utility. Sensitivity of the ICIQ-UAB to the severity of the condition was supported (known groups validity), and correlations with concurrent PROMs were as expected, showing evidence of construct validity. All domains demonstrated reliability (Cronbach's α ≥ 0.88). Limited evidence for responsiveness was found, which was likely due to insufficient efficacy of trial medication treatment over administration time-points. Conclusions: The two scored domains and associated bother for the ICIQ-UAB have been shown to be reliable, valid and sensitive to the severity of the condition. The instrument can be recommended to researchers and clinicians for the comprehensive assessment of symptoms and their impact on HRQoL on patients with suspected UAB.