1 Center for Interstitial and Rare Lung Diseases, Department of Pneumology, Thoraxklinik, University of Heidelberg, Heidelberg, Germany; German Center for Lung Research, Heidelberg 69126, Germany. Electronic address: kreuter@uni-heidelberg.de.
2 Department of Rheumatology, Oslo University Hospital, Oslo, Norway; Faculty of Medicine, University of Oslo, Oslo, Norway.
3 Centre for Rare Lung Diseases, Department of Respiratory Disease and Allergy, Aarhus University Hospital, Aarhus, Denmark.