J Korean Soc Emerg Med.  2010 Feb;21(1):131-138.

Effect of the Time-related Overcrowding Factors on the Ambulance Diversion

• Cho JS
• Shin SD
• Cha WC
• Song KJ
• Ong ME

Abstract

PURPOSE
We evaluated the influence of time-related input, throughput, and output factors on ambulance diversions in an urban emergency department (ED).
METHODS
Data was prospectively collected in an urban ED for one year. We measured daily input factors (daily number of visit, etc), throughput factors (ED length of stay), and output factors (occupancy rate of adult ward, etc). The duty emergency physician had the authority to declare an ambulance diversion. There was no written protocol for ambulance diversion, and each diversion lasted 4 hours if not extended. We estimated the effect of the potential factors of the same day and the previous day on ambulance diversion with a multivariates logistic regression analysis excluding variables with collinearity
RESULTS
The total annual number of visits was 40,863. The number of patients delivered by ambulance was 4,059 (9.9%). Ambulance diversion occurred 29 times during 365 twenty-four hour observation intervals (7.9%). The multivariates logistic regression analyses revealed three significant independent factors of ambulance diversion: the ward occupancy rate of the previous day (odds ratio [OR], 1.278; 95% confidence interval [CI], 1.039-1.573), the elderly proportion for the day (OR, 1.106; 95% CI, 1.005-1.217), the total number of visits of the day (OR, 1.079; 95% CI, 1.039-1.120).
CONCLUSION
Daily number of visits, proportion of elderly, and ward occupancy rate of the previous day were found to be factors related with ambulance diversion, with the hospital occupancy rate of the previous day showing the highest OR.

Keyword

Hospital emergency service; Crowding; Ambulances; Time factors

MeSH Terms

Adult
Aged
Ambulances
Crowding
Emergencies
Emergency Service, Hospital
Humans
Logistic Models
Prospective Studies
Time Factors