A disease-specific quality of life instrument for non-alcoholic fatty liver disease and non-alcoholic steatohepatitis: CLDQ-NAFLD.

BACKGROUND: Non-alcoholic fatty liver disease and non-alcoholic steatohepatitis are the most common causes of chronic liver disease with known negative impact on patients' health-related quality of life. Our aim was to validate a disease-specific health-related quality of life instrument useful for efficacy trials involving patients with non-alcoholic fatty liver disease and non-alcoholic steatohepatitis.

METHODS: From a long item selection questionnaire, we selected relevant items which, by factor analysis, were grouped into domains constituting Chronic Liver Disease Questionnaire-Non-Alcoholic Fatty Liver Disease version. The developed instrument was subjected to internal validity, test-retest reliability and construct validity assessment using standard methods.

RESULTS: For development of the Chronic Liver Disease Questionnaire-Non-Alcoholic Fatty Liver Disease version instrument, a 75-item-long item selection questionnaire was administered to 25 patients with non-alcoholic fatty liver disease. After item reduction, factor analysis found that 98.7% of variance in the remaining items would be explained by six factors. Thus, the resulting Chronic Liver Disease Questionnaire-Non-Alcoholic Fatty Liver Disease version instrument had 36 items grouped into six domains: Abdominal Symptoms, Activity, Emotional, Fatigue, Systemic Symptoms, and Worry. The independent validation group included another 104 patients with non-alcoholic fatty liver disease. The Cronbach's alphas of 0.74-0.90 suggested good to excellent internal consistency of the domains. Furthermore, the presence of obesity and history of depression were discriminated best by Chronic Liver Disease Questionnaire-Non-Alcoholic Fatty Liver Disease version scores (P<.05). The domains' correlations with the most relevant domains of Short Form-36 exceeded 0.70. Test-retest reliability in a subgroup of patients (N=27) demonstrated no significant within-patient variability with multiple administrations (all median differences were zero, all P>.15, intraclass correlations .76-.88).

CONCLUSION: The Chronic Liver Disease Questionnaire-Non-Alcoholic Fatty Liver Disease version is a disease-specific health-related quality of life instrument developed and validated using an established methodology and useful for clinical trials of non-alcoholic fatty liver disease.