Reliability and validity of the Incontinence Quality of Life questionnaire in patients with neurogenic urinary incontinence.

OBJECTIVE

To assess the reliability, validity, responsiveness, and minimally important difference (MID) of the Incontinence Quality of Life (I-QOL) questionnaire in patients with urinary incontinence due to neurogenic detrusor overactivity.

DESIGN

Randomized, double-blind, multicenter, placebo-controlled study.

SETTING

Eight centers across Belgium, France, and Switzerland.

PARTICIPANTS

Patients with urinary incontinence due to neurogenic detrusor overactivity inadequately managed on oral anticholinergics. Fifty-nine patients (spinal cord injury, n=53; multiple sclerosis, n=6) were enrolled.

INTERVENTION

Single dose of botulinum toxin type A (Botox) (200 or 300 U) or placebo.

MAIN OUTCOME MEASURES

I-QOL questionnaire completed at screening and over a 24-week post-treatment period.

RESULTS

The Cronbach alpha ranged from .79 to .93, indicating that I-QOL is a reliable measure of QOL in neurogenic urinary incontinence patients. No item had more than 5.1% missing or out of range values. With the exception of 2 items, questions showed acceptable item-scale correlation and scaling success results varied by domain. Post-treatment correlations indicated acceptable construct validity. The I-QOL was responsive to improvements in symptoms. MID values ranged from 4 to 11 points.

CONCLUSIONS

Results suggest that I-QOL is a reliable, valid, and responsive measure of incontinence-related QOL in neurogenic patients.