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: leep."

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.