[Data linkage of primary and secondary data: a gain for small-area health-care analysis?].

In Germany, research on health-care services addresses many topics within a regional context, and it predominantly uses a single (typically secondary) data sources for this purpose. The specific disadvantages and methodological challenges associated with these data sources may limit analysis. Various data sources break the data down by region and may be of interest in regional health-care research. Linking multiple data sources (data linkage) could therefore expand analysis options in this area. Researchers in this field are currently discussing various approaches for using data linkage to overcome the respective weaknesses of primary and secondary data. This contribution covers the various types of data linkage (on an aggregate or individual level) and their potentials and limitations in small area health services research. The focus lies on individual data linkage, which requires written informed consent. Taking into account methodological and particularly data protection challenges, conclusions are drawn regarding future application areas and options of small area health services research and specific examples are provided.