Quality-of-life measures in fecal incontinence: Is validation valid?

BACKGROUND: Multiple health measurement scales have been used to study patients with fecal incontinence, but none have met the needs for clinical use and research perfectly. These include severity scales and generic and condition-specific quality-of-life scales. Several different approaches have been used to develop and evaluate the internal and external validity of these scales. OBJECTIVE: As a step toward an improved quality-of-life instrument for fecal incontinence, the present study aimed to provide a critical review of the psychometric methodology of existing generic and condition-specific quality-of-life scales by using a standard measurement model. DESIGN: This study is a retrospective review. SETTINGS: Two investigators experienced in psychometric methodology reviewed source articles from frequently used fecal incontinence quality-of-life scales. PATIENTS: Patients with fecal incontinence were identified. MAIN OUTCOME MEASURES: The primary outcome measured was the demonstration of at least 1 reliability criterion, content validity, construct validity, and either criterion validity or discriminative validity. RESULTS: A total of 12 scales were identified. The reported methodology varied considerably. Most scales demonstrated convergent validity and test-retest reliability, whereas very few scales demonstrated internal consistency or predictive validity. Generic scales were found to be reliable and valid, but not responsive to condition severity. There was a wide range of methodology used in scale development and a wide diversity in the psychometric rigor. LIMITATIONS: Variations in scale construction, data reporting, and validity testing made the evaluation of fecal incontinence quality-of -life scales by using a standardized measurement model difficult. CONCLUSIONS: Identifying deficiencies in validity testing and reporting of existing scales is vital for future creation of a useful validated instrument to measure quality of life in patients with fecal incontinence.