Abstract
BackgroundOveractive bladder is a prevalent and burdensome condition. Generic utility measures may fail to reflect its full impact on patients’ health status. The Incontinence Utility Index (IUI) is a community-based preference index derived from the Incontinence Quality of Life Questionnaire (I-QOL) developed to value health states related to urinary symptoms in patients with neurogenic detrusor overactivity. This study assessed the measurement properties of the IUI in patients with idiopathic overactive bladder (OAB).MethodsData were used from two clinical trials which recruited patients with OAB whose symptoms were inadequately managed with ≥1 anticholinergic medication. Psychometric evaluation included: Differential Item Functioning (DIF) analysis, concordance between I-QOL and IUI (Intraclass correlation coefficient [ICC], criterion and convergent validity according to relevant patient reported outcomes and clinical variables (Spearman’s correlation coefficient, rho), responsiveness, and agreement between utility measures (ICC and Bland-Altman method).ResultsA total of 1,105 idiopathic OAB patients were included. Mean age (range) was 60.4 years (18–90), 87.8 % (n = 970) were female. DIF was identified in 3 items, none of which are contained in the IUI. ICC (CI95 %) was 0.944 (0.936–0.950). Statistically significant differences (p < 0.001) were found in IUI scores for patients improving according to the Treatment Benefit Scale (TBS). Moderate to strong correlations (rho > |0.6|) were found in the expected direction with daily incontinence, urgency episodes and disease-specific domains of King’s Health Questionnaire (KHQ). Low to moderate correlations (rho:<|0.6|) were found with Short Form version 2 (SF-12v2) summary components. A large effect size was found for patients reporting improvement (0.98–1.21) or great improvement (1.87–2.56) in the TBS, as well as in patients responding to treatment (1.19–2.40). Across utility measures, directional trends were consistent with OAB symptom profile, however, a lack of agreement in absolute values was observed.ConclusionsThe IUI presents good psychometric properties for valuing the impact of UI-related problems in idiopathic OAB patients.Trial registrationClinicalTrials.gov: NCT00910845 and NCT00910520.
Highlights
Overactive bladder is a prevalent and burdensome condition
Previous research has shown that overactive bladder (OAB), especially when accompanied with urinary incontinence (UI) or urgency urinary incontinence (UUI), considerably impacts patients’ health related quality of life (HRQoL) [6,7,8,9], affecting domains related to emotional well-being and social participation [7, 8], and resulting in decreased work productivity [7, 10, 11]
This study presents the measurement properties of the Incontinence Utility Index (IUI) in a sample of idiopathic OAB patients with UI
Summary
Sample OAB cases included in the present analysis were adult patients with idiopathic OAB and UI, participating in two multicenter, international, Phase 3, randomized, double-blind, placebo-controlled studies to evaluate the safety and efficacy of a single treatment of BOTOX® (onabotulinumtoxinA, Allergan Inc.). Further tests were applied to assess the psychometric performance of the abbreviated health state classification defined in the IUI and the associated utility scores in this sample of OAB patients. Responsiveness The ability of the abbreviated form of the I-QOL and the IUI to capture clinically relevant changes in OAB patients were analyzed according to the level of response to treatment and TBS scale. To this end, differences in scores between baseline and Week 12 visits were calculated via Wilcoxon tests, standardized response means (SRMs) and effect size statistics. The statistical packages SPSS 21.0 and Winsteps 3.75 were used to conduct the analyses above
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