1. Medisch Spectrum Twente; Department of Pulmonary Medicine; Haaksbergerstraat 55 Enschede Netherlands 7513 ER
2. Radboud University Medical Center; Department for Health Evidence; PO Box 9101 Nijmegen Netherlands 6500 HB
3. University Medical Center Utrecht; Julius Center for Health Sciences and Primary Care; PO Box 85500 Utrecht Netherlands 3508 GA
4. University of Twente; Department of Research Methodology, Measurement and Data Analysis; Enschede Netherlands
5. Repatriation General Hospital; Respiratory Clinical Research Unit; Daw Park South Australia Australia
6. Flinders University; School of Medicine; Adelaide South Australia Australia