title: National trends in the utilization of emergency medical services for acute myocardial infarction and stroke.
abstract: BACKGROUND
  The emergency medical services (EMS) system plays a crucial role in the chain of survival for acute myocardial infarction (AMI) and stroke. While regional studies have shown underutilization of the 911 system for these time-sensitive conditions, national trends have not been studied. Our objective was to describe the national prevalence of EMS use for AMI and stroke, examine trends over a six-year period, and identify patient factors that may contribute to utilization.
  
  
  METHODS
  Using the National Hospital Ambulatory Medical Care Survey-ED (NHAMCS) dataset from 2003-2009, we looked at patients with a discharge diagnosis of AMI or stroke who arrived to the emergency department (ED) by ambulance. We used a survey-weighted χ2 test for trend and logistic regression analysis.
  
  
  RESULTS
  In the study, there were 442 actual AMI patients and 220 (49.8%) presented via EMS. There were 1,324 actual stroke patients and 666 (50.3%) presented via EMS. There was no significant change in EMS usage for AMI or stroke over the six-year period. Factors independently associated with EMS use for AMI and stroke included age (OR 1.21; 95% CI 1.12-1.31), Non-Hispanic black race (OR 1.72; 95% CI 1.16-2.29), and nursing home residence (OR 11.50; 95% CI 6.19-21.36).
  
  
  CONCLUSIONS
  In a nationally representative sample of ED visits from 20003-2009, there were no trends of increasing EMS use for AMI and stroke. Efforts to improve access to care could focus on patient groups that underutilize the EMS system for such conditions.
authors.affiliation: University of California at San Francisco, Department of Emergency Medicine, San Francisco, California.
authors.forename: Katie
authors.initials: K
authors.lastname: Tataris
authors.affiliation: University of California at San Francisco, Department of Emergency Medicine, San Francisco, California.
authors.forename: Sean
authors.initials: S
authors.lastname: Kivlehan
authors.affiliation: University of California at San Francisco, Department of Emergency Medicine, San Francisco, California.
authors.forename: Prasanthi
authors.initials: P
authors.lastname: Govindarajan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004632:Emergency Medical Services / Q000706:statistics & numerical data* / Q000639:trends; D005260:Female; D006266:Health Education / Q000458:organization & administration; D007722:Health Knowledge, Attitudes, Practice; D006302:Health Services Research; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology*; D010343:Patient Admission / Q000706:statistics & numerical data*; D015995:Prevalence; D020521:Stroke / Q000453:epidemiology*; D013997:Time Factors; D014481:United States / Q000453:epidemiology