[1] Seoul Natl Univ, Seoul Natl Univ Hosp, Dept Anesthesiol & Pain Med, Coll Med, 101 Daehak Ro, Seoul 03080, South Korea
[2] Seoul Natl Univ, Seoul Natl Univ Hosp, Dept Internal Med, Coll Med, Seoul, South Korea
[3] Sungkyunkwan Univ, Dept Stat, Seoul, South Korea
[4] Seoul Natl Univ, Seoul Natl Univ Hosp, Dept Thorac & Cardiovasc Surg, Coll Med, Seoul, South Korea
[5] Seoul Natl Univ, Dept Infect Prevent & Control, Seoul Metropolitan Govt, Boramae Med Ctr, Seoul, South Korea
[6] Seoul Natl Univ Hosp, Infect Control Ctr, Seoul, South Korea