Development and Validation of a Disease-Specific Questionnaire to Assess Patient-Reported Symptoms in Polycystic Liver Disease.

UNLABELLED: Treatment of polycystic liver disease (PLD) focuses on symptom improvement. Generic questionnaires lack sensitivity to capture PLD-related symptoms, a prerequisite to determine effectiveness of therapy. We developed and validated a disease-specific questionnaire that assesses symptoms in PLD (PLD-Q). We identified 16 PLD-related symptoms (total score 0-100 points) by literature review and interviews with patients and clinicians. The developed PLD-Q was validated in Dutch (n = 200) and United States (US; n = 203) PLD patients. We assessed the correlation of PLD-Q total score with European Organization for Research and Treatment of Cancer (EORTC) symptom scale, global health visual analogue scale (VAS) of EQ-5D, and liver volume. To test discriminative validity, we compared PLD-Q total scores of patients with different PLD severity stages (Gigot classification) and PLD-Q total scores of PLD patients with general controls and polycystic kidney disease patients without PLD. Reproducibility was tested by comparing original test scores with 2-week retest scores. In total, 167 Dutch and 124 US patients returned the questionnaire. Correlation between PLD-Q total score and EORTC symptom scale (The Netherlands [NL], r = 0.788; US, r = 0.811) and global health VAS (NL, r = -0.517; US, r = -0.593) was good. There was no correlation of PLD-Q total score with liver volume (NL, r = 0.138; P = 0.236; US, r = 0.254; P = 0.052). Gigot type III individuals scored numerically higher than type II patients (NL, 46 vs. 40; P = 0.089; US, 48 vs. 36; P = 0.055). PLD patients scored higher on the PLD-Q total score than general controls (NL, 42 vs. 17; US, 40 vs. 13 points) and polycystic kidney disease patients without PLD (22 points). Reproducibility of PLD-Q was excellent (NL, r = 0.94; US, 0.96). CONCLUSION: PLD-Q is a valid, reproducible, and sensitive disease-specific questionnaire that can be used to assess PLD-related symptoms in clinical care and future research. (Hepatology 2016;64:151-160).