Health and Care Data: Approaches to data linkage for evidence-informed policy.

An indispensable prerequisite for answering research questions in health services research is the availability and accessibility of comprehensive, high-quality data. It can be assumed that health services research in the coming years will be increasingly based on data linkage, i.e., the linking, or connecting, of several data sources based on suitable common key variables. A range of approaches to data collection, storage, linkage and availability exists across countries, particularly for secondary research purposes (i.e., the use of data initially collected for other purposes), such as health systems research. The main goal of this review is to develop an overview of, and gain insights into, current approaches to linking data sources in the context of health services research, with the view to inform policy, based on existing practices in high-income countries in Europe and beyond. In doing so, another objective is to provide lessons for countries looking for possible or alternative approaches to data linkage. Thirteen country case studies of data linkage approaches were selected and analysed. Rather than being comprehensive, this review aimed to identify varied and potentially useful case studies to showcase different approaches to data linkage worldwide. A conceptual framework was developed to guide the selection and description of case studies. Information was first identified and collected from publicly available sources and a profile was then created for each country and each case study; these profiles were forwarded to appropriate country experts for validation and completion. The report presents an overview of the included countries and their case studies (Chapter 2), with key data per country and case study in the appendices. This is followed by a closer look at the possibilities of using routine data (Chapter 3); the different approaches to linkage (Chapter 4); the different access routes for researchers (Chapter 5); the use of data for research from electronic patient or health records (Chapter 6); foundational considerations related to data safety, privacy and governance (Chapter 7); recent developments in cross-border data sharing and the European Health Data Space (Chapter 8); and considerations of changes and responses catalysed by the COVID-19 pandemic as related to the generation and secondary use of data (Chapter 9). The review ends with overall conclusions on the necessary characteristics of data to inform research relevant for policy and highlights some insights to inspire possible future solutions - less or more disruptive - for countries looking to expand their use of data (Chapter 10). It emphasises that investing in data linkage for secondary use will not only contribute to the strengthening of national health systems, but also promote international cooperation and contribute to the international visibility of scientific excellence.