1. Institute for Research in Operative Medicine, Witten/Herdecke University, Cologne, Germany.
2. Medexo GmbH—Medical Experts Online, Berlin, Germany.
3. Faculty of Health Sciences Brandenburg, Brandenburg Medical School, Neuruppin, Brandenburg, Germany.
4. Center for Health Services Research, and Institute for Health Services and Health System Research, Brandenburg Medical School (Theodor Fontane), Rüdersdorf, Germany.
5. Faculty of Health Sciences Brandenburg, Institute for Health Services and Health System Research, Brandenburg Medical School (Theodor Fontane), Rüdersdorf, Germany.