title: Characterizing the vulnerability of frequent emergency department users by applying a conceptual framework: a controlled, cross-sectional study.
abstract: BACKGROUND
  Frequent emergency department (ED) users meet several of the criteria of vulnerability, but this needs to be further examined taking into consideration all vulnerability's different dimensions. This study aimed to characterize frequent ED users and to define risk factors of frequent ED use within a universal health care coverage system, applying a conceptual framework of vulnerability.
  
  
  METHODS
  A controlled, cross-sectional study comparing frequent ED users to a control group of non-frequent users was conducted at the Lausanne University Hospital, Switzerland. Frequent users were defined as patients with five or more visits to the ED in the previous 12 months. The two groups were compared using validated scales for each one of the five dimensions of an innovative conceptual framework: socio-demographic characteristics; somatic, mental, and risk-behavior indicators; and use of health care services. Independent t-tests, Wilcoxon rank-sum tests, Pearson's Chi-squared test and Fisher's exact test were used for the comparison. To examine the -related to vulnerability- risk factors for being a frequent ED user, univariate and multivariate logistic regression models were used.
  
  
  RESULTS
  We compared 226 frequent users and 173 controls. Frequent users had more vulnerabilities in all five dimensions of the conceptual framework. They were younger, and more often immigrants from low/middle-income countries or unemployed, had more somatic and psychiatric comorbidities, were more often tobacco users, and had more primary care physician (PCP) visits. The most significant frequent ED use risk factors were a history of more than three hospital admissions in the previous 12 months (adj OR:23.2, 95%CI = 9.1-59.2), the absence of a PCP (adj OR:8.4, 95%CI = 2.1-32.7), living less than 5 km from an ED (adj OR:4.4, 95%CI = 2.1-9.0), and household income lower than USD 2,800/month (adj OR:4.3, 95%CI = 2.0-9.2).
  
  
  CONCLUSIONS
  Frequent ED users within a universal health coverage system form a highly vulnerable population, when taking into account all five dimensions of a conceptual framework of vulnerability. The predictive factors identified could be useful in the early detection of future frequent users, in order to address their specific needs and decrease vulnerability, a key priority for health care policy makers. Application of the conceptual framework in future research is warranted.
authors.affiliation: Vulnerable Populations Center, Department of Ambulatory Care and Community Medicine, University of Lausanne & Lausanne University Hospital, Lausanne, CH-1015, Switzerland. patrick.bodenmann@hospvd.ch.
authors.forename: Patrick
authors.initials: P
authors.lastname: Bodenmann
authors.affiliation: Life Course and Inequality Research Center, Faculty of Social and Political Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland. stephanie.baggio@unil.ch.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Baggio
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, CH-1011, Switzerland. katia.iglesias@unine.ch.
authors.forename: Katia
authors.initials: K
authors.lastname: Iglesias
authors.affiliation: Vulnerable Populations Center, Department of Ambulatory Care and Community Medicine, University of Lausanne & Lausanne University Hospital, Lausanne, CH-1015, Switzerland. Fabrice.Althaus@hospvd.ch.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Althaus
authors.affiliation: Institute of Higher Education and Research in Healthcare, Lausanne University Hospital, Lausanne, CH-1010, Switzerland. venetia.velonaki@chuv.ch.
authors.forename: Venetia-Sofia
authors.initials: VS
authors.lastname: Velonaki
authors.affiliation: Addiction Switzerland, Research Institute, Lausanne, CH-1001, Switzerland. Stephanie.Stucki@chuv.ch.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Stucki
authors.affiliation: Department of Community Medicine and Public Health, Lausanne University Hospital, Lausanne, CH-1011, Switzerland. corine.ansermet@hospvd.ch.
authors.forename: Corine
authors.initials: C
authors.lastname: Ansermet
authors.affiliation: Department of Community Medicine and Public Health, Lausanne University Hospital, Lausanne, CH-1011, Switzerland. sophie.paroz@chuv.ch.
authors.forename: Sophie
authors.initials: S
authors.lastname: Paroz
authors.affiliation: Emergency Department, Lausanne University Hospital, Lausanne, CH-1011, Switzerland. lionel.trueb@chuv.ch.
authors.forename: Lionel
authors.initials: L
authors.lastname: Trueb
authors.affiliation: Emergency Department, Lausanne University Hospital, Lausanne, CH-1011, Switzerland. olivier.hugli@chuv.ch.
authors.forename: Olivier
authors.initials: O
authors.lastname: Hugli
authors.affiliation: Vulnerable Populations Center, Department of Ambulatory Care and Community Medicine, University of Lausanne & Lausanne University Hospital, Lausanne, CH-1015, Switzerland. Judith-Louise.Griffin@hospvd.ch.
authors.forename: Judith L
authors.initials: JL
authors.lastname: Griffin
authors.affiliation: Alcohol Treatment Service, Lausanne University Hospital, Lausanne, CH-1011, Switzerland. jean-bernard.daeppen@chuv.ch.
authors.forename: Jean-Bernard
authors.initials: JB
authors.lastname: Daeppen
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006296:Health Services / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D013557:Switzerland; D019472:Universal Health Insurance / Q000706:statistics & numerical data*; D035862:Vulnerable Populations / Q000706:statistics & numerical data*