Influence of Ambulance Arrival on Emergency Department Time to Be Seen

Abstract

Objectives. For a limited number of presenting complaints, arrival by ambulance has been shown in some emergency departments to decrease time to be seen by a physician. We sought to determine if this time advantage could be demonstrated as a national trend over a variety of presenting complaints. Methods. A secondary analysis was performed on the National Hospital Ambulatory Medical Care Survey, a national probability sample of emergency department visits. To compare waiting times between patients arriving by ambulance andthose arriving by walk-in, a survival analysis was performed using univariate andmultivariate Cox proportional hazards models. Primary variables of interest were mode of arrival, waiting time to see physician, andimmediacy to be seen (triage category). The weighted values were utilized to produce national estimates. Patients who left without being seen were treated as right censored data. Results. A total of 61,130 records, weighted to represent 268.3 million emergency department visits from 1997 to 2000, were included in the analysis. Patients arrived by ambulance in 14.4% of these cases. Median wait time for patients arriving by ambulance was 14.1 minutes (95% confidence interval [CI], 4.3 to 34.2) as compared with 26.0 minutes (95% CI, 11.5 to 55.1) for patients who arrived by walk-in. In the multivariate analysis, arrival by ambulance offered a 25.0% (95% CI, 19.0% to 31.6%) time advantage over walk-in anda 40.8% (95% CI, 23.5% to 58.7%) time advantage over arrival by public service. Conclusions. Arrival by ambulance offered a time to be seen advantage for a broad range of presenting complaints in the National Hospital Ambulatory Medical Care Survey across all triage categories. Key words: ambulance; EMS; emergency medical services; survival analysis; waiting time.