Background and AimsPolycystic liver disease (PLD) can lead to extensive hepatomegaly. Symptom relief is the primary goal of the treatment. The role of the recently developed disease‐specific questionnaires for identification of the thresholds and the assessment of therapy needs further investigation.MethodsA five‐year prospective multi‐centric observational study in 21 hospitals in Belgium gathered a study population of 198 symptomatic PLD‐patients of whom the disease‐specific symptom questionnaire PLD‐complaint‐specific assessment (POLCA) scores were calculated. The thresholds of the POLCA score for the need for volume reduction therapy were analyzed.ResultsThe study group consisted of mostly (82.8%) women with baseline mean age of 54.4 years ±11.2, median liver volume expressed as height‐adjusted total liver volume(htLV) of 1994 mL (interquartile range [IQR] 1275; 3150) and median growth of the liver of +74 mL/year (IQR +3; +230). Volume reduction therapy was needed in 71 patients (35.9%). A POLCA severity score (SPI) ≥ 14 predicted the need for therapy both in the derivation (n = 63) and the validation cohort (n = 126). The thresholds to start somatostatin analogues (n = 55) or to consider liver transplantation (n = 18) were SPI scores of ≥14 and ≥ 18 and the corresponding mean htLVs were 2902 mL (IQR 1908; 3964) and 3607 mL (IQR 2901; 4337), respectively. Somatostatin analogues treatment resulted in a decrease in the SPI score −6.0 versus + 4.5 in patients without somatostatin analogues (p < 0.01). Changes in the SPI score were significantly different between the liver transplantation group and no liver transplantation group, +4.3 ± 7.1 versus −1.6 ± 4.9, respectively, (p < 0.01).ConclusionA polycystic liver disease‐specific questionnaire can be used as a guide on when to start a volume reduction therapy and to assess the effect of treatment.