1. University Witten/Herdecke; Institute for Research in Operative Medicine (IFOM) - Department for Evidence-based Health Services Research; Ostmerheimer Str. 200 (Building 38) Cologne Germany 51109
2. Medical advisory service of social health insurance (MDS); Department of Evidence-based medicine; Theodor-Althoff-Straße 47 Essen North Rhine Westphalia Germany 51109