Using hospital information systems for clinical epidemiological research.

We address the question of how data collected during routine medical practice and stored in a hospital information system to support the various functions of the hospital can be used for clinical epidemiological research. The hospital information system HIS developed by BAZIS and implemented at the Leiden University Hospital is used as an example because the availability of data for clinical research is considered a potential benefit of the BAZIS-HIS. After a brief outline of the research area of clinical epidemiology and the BAZIS-HIS has been given, three different ways in which a hospital information system can be used in clinical epidemiology, are discussed: (1) as a sampling frame to select the study population; (2) to collect data from patients taking part in the study; (3) to register data specifically collected for the study. Whether or not the hospital information system is used in a particular study depends on the specific research question, the design of the study, the content of the database and the completeness and accuracy of the registration. We shall argue that retrieval facilities alone are not sufficient to support clinical research. To decide which items can best be used to select a study population, it is necessary to know how medical events take place in daily practice and how they are registered. Therefore when data stored in hospital information systems are used for epidemiological research, close collaboration is required between the clinical epidemiologists, the hospital administrative personnel and the data processing experts.