title: The survival benefit of dual dispatch of EMS and fire-fighters in out-of-hospital cardiac arrest may differ depending on population density--a prospective cohort study.
abstract: BACKGROUND
  Outcome after out-of-hospital cardiac arrest (OHCA) varies between contexts. Dual dispatching of fire-fighters or police in addition to emergency medical services (EMS) has the potential to increase survival, but the effect in urban vs. rural areas is unknown. The aim of this study was to determine the effects of dual dispatching on response times and outcome in regions with different population density.
  
  
  RESULTS
  The study design was a prospective cohort study of EMS-treated OHCAs from 2004 (historical controls, only EMS dispatch) and 2006-2009 (intervention, dual dispatch of EMS and fire-fighters), with data on exact geographical coordinates. Patients were divided into four subgroups depending on population density: rural (<250 persons/km2), suburban (250-2999/km2), urban (3000-5999/km2) and downtown (≥6000/km2). Totally, 2513 OHCAs were included (historical controls, n=571 and intervention, n=1942). Median time to arrival of first unit shortened significantly in all subgroups, ranging from 0.8 to 3.2 min, with the main time gain in the rural area. There were significant differences in 30-day survival between the historical controls vs. the intervention group in the suburban population (3.1% vs. 7.0%, p=0.02) and in downtown (4.1 vs. 14.6, p=0.04). In the urban population the difference was 2.7 vs. 6.9% (p=0.06) and in the rural population (4.7 vs. 5.3, p=0.82).
  
  
  CONCLUSIONS
  Dual dispatch of fire-fighters and EMS in OHCA significantly reduced response times in all studied regions. The 30-day survival increased significantly in the downtown and suburban populations, while a limited impact was seen in the rural areas.
authors: Department of Medicine, Karolinska Institutet, Solna, Stockholm, Sweden. Electronic address: per.nordberg@sodersjukhuset.se.
authors: Per
authors: P
authors: Nordberg
authors: Department of Medicine, Karolinska Institutet, Solna, Stockholm, Sweden.
authors: Martin
authors: M
authors: Jonsson
authors: Department of Clinical Science and Education, Karolinska Institutet, Section of Cardiology, Södersjukhuset, Stockholm, Sweden.
authors: Sune
authors: S
authors: Forsberg
authors: Department of Medicine, Karolinska Institutet, Solna, Stockholm, Sweden.
authors: Mattias
authors: M
authors: Ringh
authors: Department of Medicine, Karolinska Institutet, Solna, Stockholm, Sweden.
authors: David
authors: D
authors: Fredman
authors: Department of Medicine, Karolinska Institutet, Solna, Stockholm, Sweden.
authors: Gabriel
authors: G
authors: Riva
authors: Department of Medicine, Karolinska Institutet, Solna, Stockholm, Sweden.
authors: Ingela
authors: I
authors: Hasselqvist-Ax
authors: Department of Medicine, Karolinska Institutet, Solna, Stockholm, Sweden.
authors: Jacob
authors: J
authors: Hollenberg
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation; D015331:Cohort Studies; D004632:Emergency Medical Services; D004634:Emergency Medical Technicians; D005260:Female; D061388:Firefighters; D065386:Historically Controlled Study; D006801:Humans; D008297:Male; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality* / Q000628:therapy*; D011156:Population Density; D013548:Sweden / Q000453:epidemiology
keywords: Cardiopulmonary resuscitation; Dual dispatch; Out-of-hospital cardiac arrest; Population density