[Quality aspects in internal medicine--from anamnesis to meta-analysis]

Quality aspects get more important in internal medicine due to novel technical developments and economic constraints. In spite of an extensive research activity in clinical medicine some research aspects of quality control are new. Among these are investigations about symptoms and complaints as well as risk factors. Too much evidence might also blur the view when the necessary data might already be available from existing studies but conclusions have not been drawn to improve quality of patient care. An instrument to this end is metaanalysis compounding the results of single studies to a more meaningful result. Thus further unnecessary trials can be avoided. Finally quality control is characterized by readiness to self-criticism. Its aim is to avoid mistakes and intends to optimize medical actions whenever possible.