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.