Health services research is based on the use of primary or secondary data. While primary data is collected specifically for the purpose of research, secondary data is a "waste product" of the reimbursement of healthcare services and is used secondarily for research purposes.

Studies using primary data can specifically collect clinical and other information needed to answer the research question, but they are very time-consuming and expensive. When recruiting patients in primary data studies, selection bias can occur if a large number of study participants refuse to take part or if seriously ill or institutionalised people cannot be included in the study. A decisive disadvantage of secondary data is the limited clinical information per study participant. There is a lack of data on disease severity, laboratory values and other clinical or instrumental examination results that are relevant for the course of the disease and the evaluation of the care process. Possible inaccuracies/errors in the diagnostic documentation may make it necessary to validate the secondary data using clinical data. An integration of secondary data with clinical data from primary care in hospitals can overcome important limitations of both data sources and thus make an important innovative contribution to health services research.

Under the aforementioned framework conditions, the research project funded by the NOWETAS Foundation will integrate data from the information systems of the Oldenburg clinic (catchment area of 1.5 million people in the Weser-Ems region) with data from statutory public health insurance companies (SHI). The aim is to create an innovative data basis for healthcare research at the universities of Oldenburg and Bremen. The advantages of this database are to be demonstrated in an exemplary way using a question relating to the care of chronic heart failure (CHI).

In addition to the Department of Computing Science at the University of Oldenburg, the Bremen Institute for Prevention Research and Social Medicine (BIPS), the Centre for Social Policy (ZES) at the University of Bremen and the Clinic for Cardiology at Oldenburg Hospital are involved in the project.

The concrete components of the research project are:

• Further coordination of the project with health insurance companies, clinics and authorities
• Development of a comprehensive data protection concept
• Development of a data protection-compliant data integration concept for data extraction from the information systems of Oldenburg Hospital
• Integration of the extracted secondary data into the BIPS database
• Statistical analysis with regard to specific care issues