[Secondary data analysis in the field of epidemiology of health care. Potential and limitations].

Due to the challenges of demographic change and rising costs in the health care sector, the epidemiology of population-based health care capacity, demand and quality increasingly moves into the interest of science, politics and public. Epidemiology of health care research contains hypothesis-based analyses as well as development, implementation and evaluation of specific interventions, e.g. innovative health care concepts. The complexity of real health care situations requires the analysis of multiple dimensions. Secondary data have many advantages (e.g. availability, completeness, cost-effective access) which make them an important resource within population-based health care research. At the same time the origin and utilization of secondary data entail systematic limitations which result from earmarked data collection. Moreover, for many research questions no secondary data are available (e.g. proportion of unattended morbidity). In those cases an additional epidemiologic survey is necessary. Therefore, a substantial potential lies in the combination of primary and secondary data. Future challenges address the person-based combination of secondary data from different sources and the integration of primary and secondary data within epidemiologic and health care research.