“…PARENT JA has developed an extensive online questionnaire, aimed at gathering information on the EU registries' interoperability preparedness, which included total of 245 registries from 31 different European countries. The questionnaire consisted of 44 questions on registry metadata, establishment, governance and operating conditions, standards uses, data source(s), data sharing protocols and other interoperability-related information [8]. It was also used as a basis for creating the Registry of Registries (RoR) [9], a searchable web catalogue of EU patient registries, which also enables registry self-assessment and comparison on interoperability readiness criteria.…”