Temporal and Provincial Variation in Ambulance Use Among Patients Who Present to Acute Care Hospitals With ST-Elevation Myocardial Infarction

Abstract

BackgroundAt the first sign or symptoms consistent with an ST-elevation myocardial infarction (STEMI), patients are encouraged to call 9-1-1 and activate emergency medical services immediately. We examined: (1) temporal trends and provincial variations in the proportion of STEMI patients who arrive by ambulance; and (2) the association between patient demographic and clinical characteristics and ambulance use. MethodsHospital data for all patients 20 years or older who presented with a primary diagnosis of STEMI between April 1, 2007 and March 31, 2013 in all provinces, except Quebec, were examined to identify ambulance use rates according to year and province. ResultsAmong 67,232 STEMI hospitalizations (for 66,008 unique patients), the proportion of patients who presented by ambulance increased from 60% in fiscal year (FY) 2007 to 68% in FY 2012. In FY 2012, Alberta had the highest percentage of ambulance use (76%), followed by New Brunswick (73%) and Ontario (72%). At the province level, a higher rate of ambulance use was negatively correlated (r = −0.72; P = 0.04) with in-hospital mortality rate. Patients who presented by ambulance were older and more likely to be female. Self-presenters were more likely to be urban dwellers and present during work hours. Provincial differences in ambulance use remained after adjustment for patient characteristics, overall, and within specific patient subgroups. ConclusionsThe use of ambulance services among patients who presented with STEMI in Canada has increased significantly over the past 5 years, although significant interprovincial variation remains.