The Critical Path Institute’s Polycystic Kidney Disease Outcome Consortium (PKDOC) intends to qualify Total Kidney Volume (TKV) as a prognostic biomarker (i.e. predictive for the outcome with the current standard of treatment) to enrich the ADPKD population with the aim to conduct clinical trials more efficiently. The applicant started to work with the FDA in 2010 and initiated the discussion with the European Medicines Agency in 2013. Five observational studies including long-term outcome regarding the change in TKV over time, with or without various therapeutic interventions (such as diet, blood pressure control, cytostatics etc.) have been integrated into one database according to Clinical Data Interchange Standards Consortium (CDISC) standards.