J Korean Soc Emerg Med.  2021 Feb;32(1):77-88.

Association between the emergency department length of stay time and in-hospital mortality according to 28 diagnosis groups in patients with severe illness diagnosis codes

  • 1Department of Emergency Medicine, Korea University College of Medicine, Seoul, Korea
  • 2Department of Emergency Medicine, Dong-A University College of Medicine, Busan, Korea
  • 3Department of Emergency Medicine, Hanyang University College of Medicine, Seoul, Korea
  • 4Department of Emergency Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea


The purpose of this study was to analyze the effects of emergency department length of stay (ED LOS) on the prognosis of patients classified in 28 severe illness diagnosis code groups.
We used data from the National Emergency Department Information System (NEDIS) from 2016 to 2017. Patients with severe illness diagnosis codes as per the discharge diagnosis reports of the emergency department were included and classified into 28 diagnosis code groups. We used multiple logistic regression analysis on the various diagnosis groups to determine whether 6 hours of ED LOS was a factor influencing mortality.
Of the 18,217,034 patients in the NEDIS data, 553,918 patients were hospitalized with a severe illness code at regional or local emergency medical centers. The average ED LOS was 389 minutes in the non-survivor group and 420 minutes in the survivor group. After adjusting for confounders, ED LOS >6 hours was associated with lower mortality (odds ratio, 0.737; 95% confidence interval, 0.715-0.759). The association of ED LOS >6 hours with lower mortality was found in the diagnosis groups for acute myocardial infarction, intracranial hemorrhage, major trauma, aortic dissection, gastrointestinal bleeding/foreign bodies, intoxication, acute kidney injury, and post-resuscitation status.
In the analysis for the 28 severe disease illness code groups, ED LOS of more than 6 hours was not a factor that adversely affects the in-hospital mortality.


Diagnosis; Clinical coding; Emergency treatment; Prognosis; Length of stay
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