The Liver Disease Symptom Index 2.0; validation of a disease-specific questionnaire.

The available liver disease-specific questionnaires do address severity of symptoms but hardly evaluate how patients experience these specific symptoms during daily activities. The Liver Disease Symptom Index 2.0 (LDSI) includes 18 items that measure symptom severity and symptom hindrance in the past week. In a large survey (n = 1175) conducted in collaboration with the Dutch liver patient association, convergent and divergent construct validity and the surplus value of including symptom severity and symptom hindrance items in the LDSI were examined. The LDSI items showed expected convergent and divergent correlations with Short Form-36 (SF-36) and Multidimensional Fatigue Index-20 (MFI-20) scales. Correlations revealed only a slight to moderate overlap between LDSI items and SF-36 and MFI-20 scales. The impact of symptom severity and symptom hindrance on generic health related quality of life (HRQoL) varied in a different way across liver patients, which indicated that symptom severity items and the symptom hindrance items measure different aspects of HRQoL. We conclude that the LDSI provides information complementary to the information given by the SF-36 and the MFI-20 and that it is psychometrically sound to include both symptom severity items and symptom hindrance items in the LDSI.