title: Use of health care services by patients with co-occurring severe mental illness and substance use disorders.
abstract: BACKGROUND
  To better respond to the health care needs of people with co-occurring mental illness and substance use disorders, it is vital to understand their itinerary through the health care system.
  
  
  OBJECTIVE
  To describe the characteristics of service utilization among patients with co-occurring disorders in a large urban area.
  
  
  METHODS
  We used a sample (n= 5467) constituted from administrative and clinical databases. Those identified as having substance use disorders and psychoses were followed over 12 months with respect to their utilization of medical services. A descriptive analysis of the data and a two-step cluster analysis were undertaken.
  
  
  RESULTS
  Our analyses revealed a relatively high utilization of emergency services, outpatient clinics, private practices and hospitalization among patients with co-occurring disorders of severe mental illness and substance use. The two-step cluster analysis produced four heterogeneous groups in terms of service utilization.
  
  
  CONCLUSIONS
  This study demonstrates the need to develop strategies for organizing health care and services that are adapted to various sites of service utilization and to diverse profiles of patients with co-occurring mental illness and substance use disorders.
authors.affiliation: Université de Montréal, Public Health.
authors.forename: Marius N
authors.initials: MN
authors.lastname: Kêdoté
authors.affiliation: Groupe de Recherche Interdisciplinaire en Santé (GRIS); Université de Montréal, Department of Health Administration.
authors.forename: Astrid
authors.initials: A
authors.lastname: Brousselle
authors.affiliation: Groupe de Recherche Interdisciplinaire en Santé (GRIS); Université de Montréal, Department of Health Administration.
authors.forename: François
authors.initials: F
authors.lastname: Champagne
keywords: co-morbidity; co-occurring; mental health; service utilization; substance use disorders