1. Department of Pediatric Pulmonology and Pediatric Allergology Beatrix Children’s Hospital University Medical Center Groningen University of Groningen Groningen The Netherlands
2. Groningen Research Institute for Asthma and COPD (GRIAC) University Medical Center Groningen University of Groningen Groningen The Netherlands
3. Department of Epidemiology University Medical Center Groningen University of Groningen Groningen The Netherlands