[Linking survey data with routine health and accident insurance data]

Data of the social security institutions, although gathered for administrative purposes, provide important information on work-related morbidity. The validity of the data can be improved by linking several data sources and data from questionnaires or medical examinations. Hence, within the framework of the "Cooperative Programme Occupation and Health" (KOPAG) a specific procedure for data linkage was developed. Data linkage was effected via an anonymous social security number on the one hand, and on the other hand a constructed short number using informations on birthday, sex, and the first letter of the surname of the employees. By means of this short number an average 62% of the questionnaires could be linked to the health insurance sickness leave data. Data linkage was particularly successful (85%) under specific advantageous conditions. Data linkage failed in 25% of all cases because the information necessary to construct the short number was obviously wrong. In general, this procedure to link survey data to routine data of the social security proves suitable for use in routine health reporting.