title: The effects of ambulance diversion: a comprehensive review.
abstract: OBJECTIVE
  To review the current literature on the effects of ambulance diversion (AD).
  
  
  METHODS
  The authors performed a systematic review of AD and its effects. PubMed, EMBASE, the Cochrane database, societal meeting abstracts, and references from relevant articles were searched. All articles were screened for relevance to AD.
  
  
  RESULTS
  The authors examined 600 citations and reviewed the 107 articles relevant to AD. AD is a common occurrence that is increasing in frequency. AD is associated with periods of emergency department (ED) crowding (Mondays, mid-afternoon to early evening, influenza season, and when hospitals are at capacity). Interventions that redesign the AD process or that provide additional hospital or ED resources reduce diversion frequency. AD is associated with increased patient transport times and time to thrombolytics but not with mortality. AD is associated with loss of estimated hospital revenues. Short of anecdotal or case reports, no studies measured the effect of AD on ED crowding, morbidity, patient and provider satisfaction, or EMS resource utilization.
  
  
  CONCLUSIONS
  Despite its common use, there is a relative paucity of studies on the effects of AD. Further research into these effects should be performed so that we may understand the role of AD in the health system.
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA. jpham3@jhmi.edu
authors.forename: Julius Cuong
authors.initials: JC
authors.lastname: Pham
authors.forename: Ronak
authors.initials: R
authors.lastname: Patel
authors.forename: Michael G
authors.initials: MG
authors.lastname: Millin
authors.forename: Thomas Dean
authors.initials: TD
authors.lastname: Kirsch
authors.forename: Arjun
authors.initials: A
authors.lastname: Chanmugam
mesh_terms: D000552:Ambulances / Q000706:statistics & numerical data*; D003441:Crowding; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006801:Humans; D014187:Transportation of Patients / Q000706:statistics & numerical data*