title: Effectiveness of interventions targeting frequent users of emergency departments: a systematic review.
abstract: OBJECTIVE
  Frequent users of emergency departments (EDs) are a relatively small group of vulnerable patients accounting for a disproportionally high number of ED visits. Our objective is to perform a systematic review of the type and effectiveness of interventions to reduce the number of ED visits by frequent users.
  
  
  METHODS
  We searched MEDLINE, EMBASE, CINAHL, PsychINFO, the Cochrane Library, and ISI Web of Science for randomized controlled trials, nonrandomized controlled trials, interrupted time series, and controlled and noncontrolled before-and-after studies describing interventions targeting adult frequent users of EDs. Primary outcome of interest was the reduction in ED use. We also explored costs analyses and various clinical (alcohol and drug use, psychiatric symptoms, mortality) and social (homelessness, insurance status, social security support) outcomes.
  
  
  RESULTS
  We included 11 studies (3 randomized controlled trials, 2 controlled and 6 noncontrolled before-and-after studies). Heterogeneity in both study designs and definitions of frequent users precluded meta-analyses of the results. The most studied intervention was case management (n=7). Only 1 of 3 randomized controlled trials showed a significant reduction in ED use compared with usual care. Six of the 8 before-and-after studies reported a significant reduction in ED use, and 1 study showed a significant increase. ED cost reductions were demonstrated in 3 studies. Social outcomes such as reduction of homelessness were favorable in 3 of 3 studies, and clinical outcomes trended toward positive results in 2 of 3 studies.
  
  
  CONCLUSIONS
  Interventions targeting frequent users may reduce ED use. Case management, the most frequently described intervention, reduced ED costs and seemed to improve social and clinical outcomes. It appears to be beneficial to patients and justifiable for hospitals to implement case management for frequent users in the framework of a clear and consensual definition of frequent users and standardized outcome measures.
authors.affiliation: Vulnerable Population Unit, Department of Ambulatory Care and Community Medicine, University of Lausanne, Lausanne, Switzerland. fabrice.althaus@unil.ch
authors.forename: Fabrice
authors.initials: F
authors.lastname: Althaus
authors.forename: Sophie
authors.initials: S
authors.lastname: Paroz
authors.forename: Olivier
authors.initials: O
authors.lastname: Hugli
authors.forename: William A
authors.initials: WA
authors.lastname: Ghali
authors.forename: Jean-Bernard
authors.initials: JB
authors.lastname: Daeppen
authors.forename: Isabelle
authors.initials: I
authors.lastname: Peytremann-Bridevaux
authors.forename: Patrick
authors.initials: P
authors.lastname: Bodenmann
mesh_terms: D000328:Adult; D019090:Case Management; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006300:Health Services Misuse; D006703:Ill-Housed Persons; D017721:Hospital Costs; D006801:Humans; D017057:Medically Uninsured; D012959:Socioeconomic Factors