Background: Many previous studies demonstrate that overcrowding is a major problem in Emergency Department (ED) around the world. There is no definition in Thailand hospitals to describe prolonged length of stay in EDs. A study is needed to understand which factors impact ED patients and to what extent this occurs.

Objective: To determine the factors associated with prolonged length of stay in Public Tertiary Military Royal Thai Air Force Hospital.

Material and Method: A cross-sectional study using routinely collected data involving non-traumatic patients presenting to the ED of Bhumibol Adulyadej Hospital, Bangkok over the 6-month period between March and August 2015. The medical records of 2,079 patients were reviewed. Key data were recorded, including patient characteristics, types of health insurance, times of presenting to emergency room, day (weekday/weekend), triage categories, and underlying disease and disease complexity using the Charlson comorbidity index (CCI) along with diagnosis categories.

Results: Univariate analysis revealed several factors that affect ED length of stay. Age, type of health insurance, times of presenting to emergency room, weekend, triage categories, and CCI were all identified as potentially important (p<0.2) and subsequently entered into the multivariable cox regression model. The multivariate model identified age, weekend, underlying disease, and disease complexity, and time of day as all significant predictors of ED length of stay. For every 10 years older a patient is, the chance of discharge is 10% less (HR = 0.90, 95% CI 0.88 to 0.92, p<0.001). Those admitted on the weekend had 1.18 times the chance of discharge (at any given time) compared to those presenting on weekdays (HR = 1.18, 95% CI 1.07 to 1.29, p<0.001), and those in the evening shift had a lower chance of discharge compared to those in day shift (Evening shift HR = 0.83, 95% CI 0.75 to 0.92, p<0.001) Finally, patients with CCI of 3 or more had a 9% less chance of discharge, compare to patients with CCI of 0 to 2 (HR = 0.91, 95% CI 0.88 to 0.94, p<0.001). The Kaplan-Meier curves found that triage categories ESI1, ESI2, ESI3 have similar discharge times (a median of approximated 400 minutes), whereas ESI4 and ESI5 patients had a considerably lower median discharge time (340 and 200 minutes, respectively).

Conclusion: The majority of patients spent long length of stay in the emergency room and almost all factors in the present study were shown to be associated with prolonged length of stay in the ED. However, the downstream effect of extended ED stay on patient safety and mortality needs further research.

Keywords: Factors, Length of stay, Non-trauma patients, Emergency Department