Validity and reliability of the Italian version of the Chronic Liver Disease Questionnaire (CLDQ-I) for the assessment of health-related quality of life.

Background: The Chronic Liver Disease Questionnaire is a specific health-related quality of life assessment designed for patients with liver diseases.

Aim: The aim of this paper is to report on the validity, reliability and sensitivity to change of the Italian version (Chronic Liver Disease Questionnaire-I) in subjects with HCV infection.

Subjects: The Chronic Liver Disease Questionnaire-I was administered to 350 subjects with HCV infection together with the World Health Organization Quality of Life Assessment, abbreviated version, a generic quality of life assessment.

Methods: The instrument was translated from English, backtranslated and reviewed in focus groups in the framework of a large multicentre study. Exploratory factor analysis identified five factors accounting for 65% of the variance of Chronic Liver Disease Questionnaire-I items and only partially overlapping with those found in the original version.

Results: The Chronic Liver Disease Questionnaire-I proved to discriminate between subjects with and without comorbid diseases at baseline (t-test = 3.59, p < 0.001). Test-retest reliability was moderate (ICC = 0.60). The Chronic Liver Disease Questionnaire-I was sensitive to change in patients who deteriorated after one month of treatment. Change in the overall Chronic Liver Disease Questionnaire-I score in deteriorated patients was correlated with changes in World Health Organization Quality of Life Assessment, abbreviated version scores in the physical, psychological and environment, but not in the social area.

Conclusions: The Italian version of Chronic Liver Disease Questionnaire is a valid and reliable instrument to be used in cross-sectional and longitudinal studies.