To evaluate the measurement properties of the EuroQoL EQ-5D and two condition-specific patient-reported outcome measures—the Symptom Severity Index (SSI) and the Urinary Incontinence-Specific Quality of Life instrument (I-QoL)—in women with urinary incontinence.
A questionnaire comprising all instruments was completed by women taking part in a clinical trial of physiotherapy for urinary incontinence. Follow-up questionnaires were at 6 weeks and 5 months. Data quality, internal consistency reliability, validity and responsiveness were assessed.
One hundred and seventy-four patients taking part in the clinical trial completed the questionnaire. Instruments had low levels of missing data. The EQ-5D had a large ceiling effect and poor responsiveness. The SSI had poor validity and responsiveness. The I-QoL had levels of reliability that supported application in group assessment, and in some cases, individual assessment, and good evidence of validity. The I-QoL was the most responsive instrument at both 6 weeks and 5 months.
The I-QoL was the best performing instrument and is recommended as a continence-specific measure of quality of life in a clinical trial setting. The SSI and EQ-5D are not recommended. Alternative generic instruments, which support economic evaluation, require further evaluation in trials of female urinary incontinence.