Irritable bowel syndrome-specific health-related quality of life instrument: development and psychometric evaluation

BACKGROUND Health-related quality of life (HRQOL) is an important outcome indicator for chronic disease, and particularly in the absence of biological markers for illness, such as with irritable bowel syndrome (IBS). The aims of this study were to develop and evaluate a new IBS-specific HRQOL instrument (IBS-HR-QOL). METHODS This methodological study comprised three steps: conceptualization of the IBS-HR-QOL, item extraction and establishment of content validity, and psychometric evaluation of the instrument with 267 IBS patients recruited from four university hospitals. RESULTS The content validity of the developed IBS-HR-QOL was assessed by 11 experts. Exploratory and confirmatory factor analyses yielded four factors. The criterion and convergent validities of the IBS-HR-QOL were demonstrated using the Short Form-36 and the Hospital Anxiety and Depression Scale, respectively. Known-groups validity was demonstrated using a symptom-severity scale. The internal consistency reliability and test-retest reliability were satisfactory, with a Cronbach's alpha and intraclass correlation coefficient of 0.93 and 0.88, respectively. CONCLUSIONS The IBS-HR-QOL comprises a total of 16 items. The IBS-HR-QOL demonstrated good psychometric properties. This instrument is easily comprehensible and short, rendering it feasible for use in clinical practice and research.