- Correspondence to Dr Jae Jeong Shim, Department of Internal Medicine, Division of Respiratory and Critical Care Medicine, Korea University Guro Hospital, Korea University College of Medicine, 148 Gurodong-ro, Seoul, Guro-gu 08308, Republic of Korea;
- Received 15 May 2017
- Revised 19 July 2017
- Accepted 24 July 2017
- Published online 11 August 2017.