The existing International Consultation on Incontinence Questionnaires (ICIQ) for lower urinary tract symptoms (LUTS) are sex-specific (ICIQ-FLUTS and ICIQ-MLUTS) [1,2]. To support standardised assessment across sexes in clinical and research settings, the ICIQ-MLUTS and ICIQ-FLUTS were combined into one universally applicable, sex-inclusive questionnaire. The current study aims to evaluate the measurement properties of the ICIQ-LUTS, following earlier cognitive debriefing interviews, through psychometric evaluation of its structural validity and reliability.

Cognitive interviews using the ‘think aloud’ technique were conducted with a purposive sample of adult, non-catheter-using patients with current LUTS, recruited from urology outpatient clinics in one UK hospital. For the subsequent psychometric validation, adults (>18), presenting with LUTS, also non-catheter users, were recruited to complete the study questionnaires. Study invitations were sent via email, post or handed to patients attending urology and urogynaecology outpatient clinics in two UK, tertiary referral hospitals reflecting diverse local populations. Participants accessed the patient information sheet, consent form and questionnaire via link or QR code and were invited to complete the questionnaire again after one week to assess test-retest reliability. A preliminary exploratory factor analysis (EFA) was conducted and identified a three-factor structure of Incontinence, Voiding and Storage, which was subsequently tested using confirmatory factor analysis (CFA) in the full data set. Internal consistency was assessed using Cronbach’s alpha (α).

Four rounds of interviews were conducted with 12 patients (7 male, 5 female). Items were re-ordered and minor refinements were made in response to both clinician and patient feedback. Following this refinement stage and a preliminary EFA, further analysis was conducted on data from 232 participants (114 males, 117 females, 1 preferred not to say). Mean age was 64.3 years (SD 16.5). Data screening indicated very low levels of missing data for all symptom items (<1%). CFA model fit indices indicated poor fit, χ2(74)=297, p < .001, CFI = .85, TLI = .82, RMSEA = .114 (90% CI [.101, .128]), SRMR = .11. Modification indices suggested potential cross-loadings for four items. Standardised factor loadings were moderate to strong across domains (λ = .40–.89). Factor covariances showed strong overlap between Incontinence and Storage (0.67, 95% CI [0.54–0.80]), a moderate association between Voiding and Storage (0.30, 95% CI [0.13–0.47]) and a small negative relationship between Incontinence and Voiding (–0.16, 95% CI [–0.30, –0.01]). Cronbach’s alpha indicated strong reliability for the Incontinence (α = 0.89) and Voiding (α = 0.82) domains, and lower internal consistency for the Storage domain (α = 0.57).

Cognitive debriefing interviews showed evidence that the 15 questionnaire items were understood, clinically relevant and interpreted as intended by male and female patients. In the psychometric data analysis, the hypothesised three-factor structure demonstrated moderate to strong item loadings, consistent with clinically defined domains. However, the model fit was poor, with modification indices suggesting potential cross-loadings for several items and substantial covariance between domains. These findings reflect the known multidimensional and overlapping nature of LUTS, and support domain-level interpretation. Internal consistency was high for the Incontinence domain and good for the Voiding domain, while the lower reliability for the Storage domain likely reflects the known heterogeneity of storage-related LUTS, which may not always co-occur. Measurement invariance across sexes is currently being evaluated.

The analyses support a clinically informed three-domain framework (Incontinence, Voiding, Storage), consistent with the symptom overlap typically observed in LUTS and reported in previous research [3]. The results support clinically meaningful domain-level interpretation. The ICIQ-LUTS is a unified, sex-inclusive measure that can be used in both men and women to characterise LUTS, supporting assessment and monitoring over time.

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Continence 19S (2026) 102619
DOI: 10.1016/j.cont.2026.102619