1. I‐BioStat KU Leuven Leuven B‐3000 Belgium
2. I‐BioStat Universiteit Hasselt Diepenbeek B‐3590 Belgium
3. Department of Epidemiology and Public Health Sciensano Brussels BE‐1050 Belgium
4. Paediatric Pulmonology and CF Unit, Hippokration Hospital of Thessaloniki Aristotle University of Thessaloniki Thessaloniki Greece
5. University Hospital Gasthuisberg, University of Leuven Leuven Belgium