Impact of Ambulance Transportation on Resource Use in the Emergency Department

OBJECTIVE: To determine how ambulance transportation is associated with resource use in the emergency department (ED). METHODS: A retrospective administrative database review of patient visits to a Montreal tertiary care hospital ED in one year (April 2000-March 2001). Measures of resource use included ED length of stay, admission to the hospital, and whether consultations and radiology/imaging tests (excluding plain-film x-rays) were ordered from the ED. RESULTS: During the study period, 39,674 patients made 59,142 visits to the ED. Ambulance transportation was used for 15.6% of these ED visits. Compared with non-ambulance visits, ambulance visits were more likely to be made by older patients (mean age: 68 vs. 47 years), to be made by females (59% vs. 55%), to have a greater triage urgency score (mean on 1-5 scale, with 1 most urgent: 2.7 vs. 3.9), and to occur after office hours, 5 PM to 9 AM (47% vs. 43%). Ambulance visits were also more likely than non-ambulance visits to result in: a longer length of stay (mean: 13.3 hours 95% CI = 13.0 to 13.6 vs. 5.9 95% CI = 5.8 to 6.0), hospital admission (40% vs. 10%) (odds ratio OR: 5.94 95% CI = 5.59 to 6.33), consultations (56% vs. 20%) (OR: 5.15 95% = 4.86 to 5.45), and radiology/imaging tests (20% vs. 12%) (OR: 1.93 95% CI = 1.81 to 2.07). In multivariate models that adjusted for the effects of age, gender, triage urgency, and temporal factors, ambulance transportation maintained its association with greater resource use. CONCLUSIONS: This preliminary study indicates that patients arriving at the ED by ambulance use significantly more resources than their walk-in counterparts.