[1] Univ Ulsan, Dept Emergency Med, Asan Med Ctr, Coll Med, Seoul 05505, South Korea
[2] Hanyang Univ, Dept Emergency Med, Coll Med, Seoul 04763, South Korea
[3] Korea Univ, Dept Emergency Med, Coll Med, Seoul 02841, South Korea
[4] Korea Univ, Dept Emergency Med, Ansan Hosp, Ansan 15355, South Korea