title: How Much Do Mental Health and Substance Use/Addiction Affect Use of General Medical Services? Extent of Use, Reason for Use, and Associated Costs.
abstract: To measure service use and costs associated with health care for patients with mental health (MH) and substance use/addiction (SA) problems.
  
  
  
  A 5-year cross-sectional study (2007-2012) of administrative health care data was conducted (average annual sample size = 123,235 adults aged >18 years who had a valid Ontario health care number and used at least 1 service during the year; 55% female). We assessed average annual use of primary care, emergency departments and hospitals, and overall health care costs for patients identified as having MH only, SA only, co-occurring MH and SA problems (MH+SA), and no MH and/or SA (MH/SA) problems. Total visits/admissions and total non-MH/SA visits (i.e., excluding MH/SA visits) were regressed separately on MH, SA, and MH+SA cases compared to non-MH/SA cases using the 2011-2012 sample ( N = 123,331), controlling for age and sex.
  
  
  
  Compared to non-MH/SA patients, MH/SA patients were significantly ( P < 0.001) more likely to visit primary care physicians (1.82 times as many visits for MH-only patients, 4.24 for SA, and 5.59 for MH+SA), use emergency departments (odds, 1.53 [MH], 3.79 [SA], 5.94 [MH+SA]), and be hospitalized (odds, 1.59 [MH], 4.10 [SA], 7.82 [MH+SA]). MH/SA patients were also significantly more likely than non-MH/SA patients to have non-MH/SA-related visits and accounted for 20% of the sample but over 30% of health care costs.
  
  
  
  MH and SA are core issues for all health care settings. MH/SA patients use more services overall and for non-MH/SA issues, with especially high use and costs for MH+SA patients.
authors.affiliation: 1 Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto/London, Ontario.|2 Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario.|3 School of Psychology, Deakin University, Geelong, Australia.|4 National Drug Research Institute, Curtin University, Perth, Australia.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Graham
authors.affiliation: 1 Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto/London, Ontario.
authors.forename: Joyce
authors.initials: J
authors.lastname: Cheng
authors.affiliation: 1 Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto/London, Ontario.
authors.forename: Sharon
authors.initials: S
authors.lastname: Bernards
authors.affiliation: 1 Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto/London, Ontario.|2 Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario.|3 School of Psychology, Deakin University, Geelong, Australia.|5 Department of Epidemiology, Western University, London, Ontario.
authors.forename: Samantha
authors.initials: S
authors.lastname: Wells
authors.affiliation: 1 Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto/London, Ontario.|2 Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario.|3 School of Psychology, Deakin University, Geelong, Australia.|6 Klinische Psychologie & Psychotherapie, Technische Universität Dresden, Dresden, Germany.|7 Department of Psychiatry, University of Toronto, Toronto, Ontario.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Rehm
authors.affiliation: 1 Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto/London, Ontario.|7 Department of Psychiatry, University of Toronto, Toronto, Ontario.|8 Institute for Clinical Evaluative Sciences, Toronto, Ontario.
authors.forename: Paul
authors.initials: P
authors.lastname: Kurdyak
mesh_terms: D000328:Adult; D015897:Comorbidity; D003430:Cross-Sectional Studies; D017831:Diagnosis, Dual (Psychiatry); D004636:Emergency Service, Hospital / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000191:economics / Q000453:epidemiology / Q000628:therapy*; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D010343:Patient Admission / Q000191:economics / Q000706:statistics & numerical data*; D011320:Primary Health Care / Q000191:economics / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000191:economics / Q000453:epidemiology / Q000628:therapy*
keywords: addiction; costs; general medical services; mental health; service use; substance use