1 Department of Pneumology, University Hospital Vienna AKH, Medical University of Vienna, Vienna, Austria.
2 Department of Medicine V, Ludwig-Maximilians-University (LMU) of Munich, Comprehensive Pneumology Center (CPC-M) German Center for Lung Research (DZL), Munich, Germany.
3 Department of Internal Medicine II - Pneumology, University Hospital Bonn, Bonn, Germany.