Validation of the Urogenital Distress Inventory (UDI-6) and Incontinence Impact Questionnaire (IIQ-7) in a Dutch population

Abstract

Aims: The Urogenital Distress Inventory (UDI-6) and Incontinence Impact Questionnaire (IIQ-7) assess symptom distress and the impact on daily life of urinary incontinence. The UDI-6 has not been validated before in males. Our aim was to validate the UDI-6 and IIQ-7 in Dutch men and women.

Methods: The translation to Dutch followed standardized procedures. We validated the IIQ-7 with and without an additional gender-neutral item (IIQ-SF). Adults with urinary incontinence for at least 3 months, completed the measures at inclusion; 1-week after inclusion to evaluate the test-retest reproducibility; and 6 months after inclusion with the addition of the RAND-36 health transition item to assess responsiveness and interpretability. To assess the discriminate ability, a reference population was enrolled. To assess construct validity, the urodynamic diagnosis was used.

Results: Questionnaire data of 160 patients were analyzed. Patients reported more symptoms and bother than the reference population (P < 0.001). The internal consistency was good in the IIQ-SF baseline scores (Cronbach's alphas 0.86-0.92), though moderate in the UDI-6 (Cronbach's alphas 0.44-0.66). Both measures showed good reproducibility at the test-retest (Intraclass Correlations Coefficients 0.75-0.85). Construct was adequate with 75% confirmed hypotheses of urodynamic data with measure scores. The measures were responsive after treatment with smaller measurement errors than the minimal important change. No floor or ceiling effects were observed in baseline data.

Conclusions: The Dutch UDI-6 and IIQ-7 are reliable, valid, and responsive instruments for assessing symptom distress of urinary incontinence and its impact on daily life in both men and women.

Keywords: psychometrics, quality of life; translations; urinary incontinence.