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Record Linkage

Record linkage is becoming more and more common in statistical and academic research. Linkage of records makes it possible to combine data from different sources to answer research questions that are very difficult or impossible to answer using data from just one source. Although linkage can be regarded as a more efficient way of obtaining data than setting up a new collection, it is important to understand the technical, methodological and legal restrictions that may apply.

The project Biolink NL aims to report on the methodological, technical and legal aspects of record linkage of health data in the Netherlands. Biolink NL is one of the so-called rainbow projects funded by the Dutch Biobanking and Biomolecular Resources Research Infrastructure (BBMRI-NL). BBMRI-NL aims to stimulate collaboration and data sharing between research institutes (mostly biobanks), building on existing infrastructures, resources and technologies. The Biolink NL project is a combined effort of researchers from a number of academic research institutes and Statistics Netherlands (CBS).


Within the field of databases, catalogues are getting more popular. Catalogues provide an overview of existing databases  and the type of subjects or data that are available. More detailed catalogues emerge as well and may contain aggregated or unaggregated data from various databases on a subject level. Catalogues can be powerful tools in the preparation of record linkage projects. Biolink NL is therefore very interested in the setup of a catalogue, which investigators can consult to estimate the feasibilitiy of a new plan and for the selection of subjects and data sources.

The following catalogue types can be distinguished *:

· Level 1 catalogue: a listing of a set of databases (e.g. biobanks or databanks);

· Level 2 catalogue: a collection of data dictionaries from a set of databases;

· Level 3 catalogue: a database containing key parameters, numbers, or data (e.g. the number of patients with breast cancer) from a set of databases;

· Level 4 catalogue: a database containing a limited number of variables on subject level from a set of databases;

· Level 5 catalogue: This is a level 4 catalogue in which the data are linked. This allows assessments which databases overlap and are suitable for record linkage.

The demands in terms of technique, knowledge on data, security, governance and privacy differ highly between the various types of catalogues. Biolink NL aims to realise two different catalogues: a level 3 and level 5 catalogue.

Key parameters – level 3 catalogue

The level 3 catalogue will be publically accessible and will be suited for a first quick scan by means of key parameters of the biobanks or databanks present in the catalogue.

Linked data on subject level - level 5 catalogue

The level 5 catalogue is a powerful tool for investigators to efficiently prepare record linkage projects. As the data are loaded in a linked manner it is possible to determine the number of subjects that overlap between two or more databases. Investigators can use it for feasibilities or selecting subjects from the different biobanks or databanks. The level 5 catalogue will be set up in cooperation with the Mondriaan Foundation (www.projectmondriaan.nl).

* classification developed by the UMC Groningen, Netherlands


When handling medical data and/or performing record linkages, privacy protection of both patients and health care professionals is not only a legal requirement but also an essential condition to safeguard the continuing cooperation of patients and professionals. Privacy protection is needed at multiple points during the handling of data and samples. This is especially true for a central catalogue and for linked records of registries and biobanks. Here identifying information from multiple sources comes together. In some situations, a risk of undesirable identification of subjects could arise. Optimal technical and procedural protocols are required to avoid this.

The ethical and legal boundaries are clear to some extent but have to be distilled from laws, case law or EU guidelines or EU working parties. Biolink NL aims to create a best-practice guideline offering practical grips regarding privacy for record linkages and catalogues. Biolink NL cooperates closely with Dr. Jasper Bovenberg on this matter. He is a well known legal expert on ELSI matters in (bio)medical research.