[Current challenges of external quality assurance in the German healthcare system].

External quality assurance has three main aims: to make service provision in medicine and nursing comparable, to systematically identify deficits in service quality and to support the introduction of measures for quality improvement. This article reflects on three major developments in mandatory external quality assurance in the German healthcare system that took place during the last five years. These developments include the implementation of cross-sectoral quality assurance, the utilisation of new data sources and a new focus on quality deficits and practicability. The article highlights the challenges that come along with these developments.