Which questionnaire? A psychometric evaluation of three patient-based outcome measures used to assess surgery for stress urinary incontinence.

Aims: The aim of the study was to further validate three patient-based outcome measures (PBOM) used to assess the outcome of surgery for stress urinary incontinence and to compare their psychometric properties with a view to determining the most appropriate measure for clinical use.

Methods: The work was embedded within a randomized controlled trial of laparoscopic and open colposuspension. The trial recruited 291 women from six centers. The three instruments compared were Bristol Female Lower Urinary Tract Symptom Questionnaire (BFLUTS), Kings Health Questionnaire (KHQ), and the Symptom Severity Index and Symptom Impact Index (SSI/SII). The International Consultation on Incontinence (ICI) ABC grading system of psychometric propertie's reliability, validity, and responsiveness was used to evaluate the instruments.

Results: From the analysis of the psychometric properties of the three instruments, the SSI/SII appeared to have the best psychometric profile; Grade A, BFLUTS was of grade A, and KHQ was of grade B. SSI/SII had a good degree of internal consistency (Cronbach's alpha 0.74-0.78). BFLUTS and KHQ both had domains in which the internal consistency was <0.7. The SSI domain of the SSI/SII was the only domain to correlate to the 1-hr pad test. All domains of the SSI/SII were able to distinguish those cured from not cured and it was most responsive to change. Unlike the KHQ, the SSI/SII had no significant ceiling or floor effects.

Conclusions: This study has demonstrated that when instruments are used in different populations their psychometric properties may change. All three instruments analyzed had limitations when used as an outcome measure for surgery for stress urinary incontinence.