1. Unit for Interstitial Lung Diseases, Department of Respiratory Medicine, University Hospitals Leuven, Leuven, Belgium
2. Department of Pulmonary Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
3. Interstitial Lung Disease Unit, Royal Brompton Hospital, London, United Kingdom
4. Department of Thoracic Medicine, Medical School, University of Crete, Crete, Greece