University of Groningen - University Medical Center Groningen (UMCG), Albert Schweitzer Hospital, Erasmus University Rotterdam (EUR) - Clinical Trial Center, University of Groningen - University Medical Center Groningen (UMCG), Medical Center Leeuwarden, Medisch Spectrum Twente, University of Groningen - University Medical Center Groningen (UMCG), University of Groningen - Groningen Research Institute for Asthma and COPD, Meander Medical Center, Tjongerschans, Antonius Zorggroep - Antonius Hospital Sneek, Deventer Ziekenhuis - Deventer Hospital, Maastricht University - Medical Center, Medical Center Leeuwarden, University of Groningen - Department of Hematology and Oncology, Independent, University of Groningen - Department of Pulmonary Diseases, Erasmus University Rotterdam (EUR) - Department of Hematology, Albert Schweitzer Hospital, University of Groningen - University Medical Center Groningen (UMCG), University of Groningen - Department of Epidemiology, Albert Schweitzer Hospital, Medical Center Leeuwarden, University of Groningen - University Medical Center Groningen (UMCG), University of Groningen - University Medical Center Groningen (UMCG), University of Groningen - University Medical Center Groningen (UMCG), University of Groningen - University Medical Center Groningen (UMCG), University of Groningen - University Medical Center Groningen (UMCG) and University of Groningen - Department of Hematology and Oncology