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

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)