The factorial structure of the Chronic Liver Disease Questionnaire (CLDQ)

Objective The Chronic Liver Disease Questionnaire (CLDQ) is a disease-specific instrument designed to assess health-related quality of life in patients with chronic liver disease. The aim of this paper is to present the psychometric properties of a German version of this questionnaire. A special focus is placed on the analysis of the CLDQ's factorial structure. Methods Five hundred and twenty-four patients completed the CLDQ from May 1999 to October 2006. The results were subject to item analysis, reliability and validity assessments, and confirmatory and exploratory factor analysis. Results The distribution characteristics on the item and scale level were satisfactory. Internal consistency was good to excellent; retest reliability acceptable. Validity could be confirmed by characteristic subscale correlations with other quality-of-life scales. Confirmatory factor analysis could not sufficiently reproduce the original factor structure. Exploratory factor analysis suggested five out of six subscales of the original version and yielded a new subscale: "sleep." Conclusion CLDQ's reliability and validity have been confirmed. In addition, the demonstrated practical administration of the questionnaire suggests that it should serve as a routine quality of life assessment of patients with chronic liver disease.