Analyzing Main and Interaction Effects of Length of Stay Determinants in Emergency Departments

Document Type : Original Article


1 Department of Business Administration, Yaşar University, İzmir, Turkey

2 Department of Emergency Medicine, Çiğli Regional Training Hospital, İzmir, Turkey

3 Department of General Surgery, Çiğli Regional Training Hospital, İzmir, Turkey


Measuring and understanding main determinants of length of stay (LOS) in emergency departments (EDs) is critical from an operations perspective, since LOS is one of the main performance indicators of ED operations. Therefore, this study analyzes both the main and interaction effects of four widely-used independent determinants of ED-LOS.
The analysis was conducted using secondary data from an ED of a large urban hospital in Izmir, Turkey. Between-subject factorial analysis of variance (ANOVA) was used to test the main and interaction effects of the corresponding factors. P values  
While the main effect of gender was insignificant, age, mode of arrival, and clinical acuity had significant effects, whereby ED-LOS was significantly higher for the elderly, those arriving by ambulance, and clinically-categorized high-acuity patients. Additionally, there was an interaction between the age and clinical acuity in that, while ED-LOS increased with age for high acuity patients, the opposite trend occurred for low acuity patients. When ED-LOS was modeled using gender, age, and mode of arrival, there was a significant interaction between age and mode of arrival. However, this interacton was not significant when the model included age, mode of arrival, and clinical acuity.
Significant interactions exist between commonly used ED-LOS determinants. Therefore, interaction effects should be considered in analyzing and modelling ED-LOS.


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Volume 9, Issue 5
May 2020
Pages 198-205
  • Receive Date: 17 January 2019
  • Revise Date: 28 October 2019
  • Accept Date: 30 October 2019
  • First Publish Date: 01 May 2020