1. Department of Clinical Immunology, RigshospitaletUniversity Hospital of Copenhagen Copenhagen Denmark
2. Danish Headache Center, Department of Neurological DepartmentCopenhagen University Hospital Glostrup Denmark
3. Department of Clinical ImmunologyNæstved Hospital Næstved Denmark
4. Department of Clinical ImmunologyUniversity Hospital of Aarhus Aarhus Denmark
5. Department of Epidemiology ResearchStatens Serum Institut, Department of Haematology, Rigshospitalet, University Hospital of Copenhagen Copenhagen Denmark
6. Department of Clinical ImmunologyOdense University Hospital Odense Denmark