1. Institute for Healthcare Management and Research University Duisburg‐Essen Essen Germany
2. Department of Otorhinolaryngology, Head and Neck Surgery, Section of Rhinology and Allergy University Hospital Marburg, Philipps‐Universität Marburg Marburg Germany
3. Center for Rhinology and Allergology Wiesbaden Germany
4. Clinic for Dermatology, Allergology and Venerology Hannover Medical School Hanover Germany
5. Department for Pediatrics, Children's Center Bethel University Bielefeld Bielefeld Germany
6. Department of Health Services Research DAK‐Gesundheit Hamburg Germany