1. Centre of Interstitial Lung Diseases, Department of Pulmonology, St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands
2. Department of Otolaryngology, Head & Neck Surgery, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
3. Division of Heart and Lungs, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands