[Procedures according to data protection laws for coupling primary and secondary data in a cohort study: the lidA study].

In the German health service research there exists, unlike in labour market research, no experience with the combination of personal primary and secondary data. One of the reasons for this is, among other things, data protection. The lidA cohort study analyses persons in employment (excluding civil servants and self-employed), born in 1959 and 1965. It is intended to give answers to questions from the health services research as well as from the labour market research. It relies on different primary and secondary data sources: survey data, process data from the Federal Employment Agency, aggregated and individual health insurance data. The experiences made in the lidA study, in addition to the data protection needs and the expenditures for the implementation, are summarised as "best practice". The procedure for the application process according to § 75 SGB X, the directive to develop data security concepts, the informed consent for the linkage of personal information are described and the importance of a transparent approach is explained. So far it has been shown that the preparation and approval process for the release of the actual data, both within the project consortium, but also with external parties such as health insurance companies or the responsible data protection officer, requires a major effort. In view of all the identified legal and organisational challenges, our findings should be extremely useful for answering different research questions in the fields of labour market and health services research. In combination with primary data, they may even represent a "gold standard" for epidemiology and health services research. © Georg Thieme Verlag KG Stuttgart · New York.