The Australian Congenital Heart Disease Registry - Linkage to National Administrative Health Data

Abstract Background Congenital Heart Disease (CHD) research must focus on outcomes that affect the whole-of-life course. To achieve this, datasets with long term follow up and patient-relevant outcomes are required. This paper reports on the linkage of The Australian and New Zealand Congenital Heart Disease Registry (ANZCHD Registry) (>80 000 unique individuals) with Australian National Administrative Health records and describes the final dataset. Methods Linkage on two cohorts was conducted by accredited linkage agencies, after all appropriate Ethics and Governance approvals. Cohort 1 included people who were identified from the ANZCHD Registry and Cohort 2 included people with an inpatient admission with a CHD diagnosis who had not been identified in Cohort 1. Healthcare events linked from 2010 to 2024 included outpatient encounters and medications, hospital admissions and emergency department presentations. Linked data was cleaned and curated to minimize the impacts of errors from the probabilistic linkage process. Results The final dataset included 94,383 subjects with structural CHD (58,523 from Cohort 1 and 35,860 from Cohort 2). There were over 35 million linked healthcare events recorded for this population, from 2010 to 2025. Cohort 1 was younger by an average of 14 years (95% CI: 13.2 – 13.9, p