Affiliation: | (1) Department of General Practice, University of Groningen, Groningen, The Netherlands;(2) Department of Pathology, University Hospital Groningen, Groningen, The Netherlands;(3) Department of Pulmonary Diseases, University Hospital Groningen, Groningen, The Netherlands;(4) Department of Clinical Epidemiology and Biostatisitics, Mc Master University of Health Sciences, Hamilton, Ontario, Canada;(5) Department of General Practice and Primary Care, University of Aberdeen, Scotland, United Kingdom |