Chronic Obstructive Pulmonary Disease

• Soonchunhyang University Bucheon Hospital — Bucheon-si, South Korea
• Inje university Pusan Paik hospital — Busan, South Korea
• Chonbuk national university hospital — Chunbuk, South Korea
• Keimyung university dongsan medical center — Daegu, South Korea

• Medical University of Vienna — Vienna, Austria

• West Park Healthcare Centre — Toronto, Ontario, Canada

• Research Site — Berlin, Germany

Not specified

• University of Illinois at Chicago — Chicago, Illinois, United States

Not specified

• Radboud University Nijmegen Medical Center, department of Pulmonary Diseases — Groesbeek, Netherlands

• Rabin Medical Center — Petach Tivka, Israel

• Dep. of Pneumology, University of Rostock — Rostock, Mecklenburg-Vorpommern, Germany