1. Institute for Medical Informatics, Biometry and Epidemiology Faculty of Medicine University Duisburg‐Essen Essen Germany
2. IRCCS C. Mondino Foundation Pavia Italy
3. Department of Brain and Behavioral Sciences University of Pavia Pavia Italy
4. Headache Clinic Neurology Clinic Tartu University Hospital Tartu Estonia
5. Faculty of Medicine University of Münster MünsterGermany
6. Krankenhaus Lindenbrunn Coppenbrügge Germany
7. Danish Headache Center Neurological Clinic Rigshospitalet‐Glostrup University of Copenhagen Copenhagen Denmark
8. Department of Neurology Hospital Clínico Universitario ValenciaSpain
9. Department of Neurology Universidad Católica de Valencia Valencia Spain
10. Department of Neurology Akershus University Hospital OsloNorway
11. Department of General Practice University of Oslo Oslo Norway
12. Department of Neurology Institute of Clinical Medicine Faculty of Medicine Vilnius University Vilnius Lithuania
13. Department Of Neurology University Hospital Zurich Zurich Switzerland