Record Linkage as a Tool for Expanding Research Opportunities: Insights from the Netherlands Twin Register and National Health and Population Data in the Netherlands

Record linkage projects provide powerful opportunities to enrich cohort data with administrative and clinical information from national registries. The Netherlands Twin Register (NTR) is a large population-based twin-family cohort with longitudinal data collection that has established multiple record linkage initiatives to expand research on genetic and environmental determinants of health, disease, behaviour, development, and fertility. In this article we summarize and discuss NTR record linkage projects. Clinical and pathology registries have provided essential data on chorionicity, reproductive history, neonatal thyroid function, and cancer diagnoses, facilitating studies on prenatal environment, disease heritability, and polygenic risk prediction for diseases. Linkage with health insurance data has enabled validation of medication use and health research. Collaborations with Statistics Netherlands allow linkage to nationwide population-based data via secure infrastructures such as Open Data Infrastructure for Social Science and Economic Innovations (ODISSEI), supporting genomewide association studies of, for example, healthcare expenditure. Finally, linkage to environmental exposure datasets has permitted exposomewide analyses of health and wellbeing. Together, these projects illustrate the feasibility, scientific value, and challenges of record linkage in the Dutch context, highlighting its role in advancing twin research, genetic epidemiology, and population health studies.