title: Opioid abuse and hospitalization rates in patients with schizophrenia.
abstract: BACKGROUND
  Substance abuse worsens the course of schizophrenia, but it is not known whether or not there are differences between specific substances concerning their association with the hospitalizations of patients with schizophrenia.
  
  
  OBJECTIVE
  The primary aims of this study were to examine the possible associations between amphetamine, cannabis, and opioid abuse, and the risk of hospitalizations among patients with schizophrenia.
  
  
  METHODS
  The study population consisted of 146 patients with ICD-defined schizophrenia from two different geographical sites in Finland, and it included both inpatients and outpatients. Data were collected retrospectively from the patients' medical files. Substance abuse was defined as either harmful use or dependence according to ICD-10.
  
  
  RESULTS
  The cumulative prevalence of substance abuse was 10.9% (16/146) for cannabis, 8.9% (13/146) for amphetamine, and 4.1% (6/146) for opioids. Among patients with schizophrenia and abuse of any substance, the number of hospitalizations was about 1.5-fold when compared to those without substance abuse. The incidence rate ratio for hospitalizations was 2.9 (95% CI 2.47-3.63) for opioids, 2.0 (1.71-2.41) for amphetamine, and 1.6 (1.33-1.84) for cannabis, when compared with no abuse of each substance. The risk of hospitalizations was significantly higher for opioids when compared with amphetamine (p < 0.001) or cannabis (p < 0.001).
  
  
  CONCLUSIONS
  Harmful use or dependence of opioids among patients with schizophrenia is associated with significantly higher risk of hospitalizations than either harmful use or dependence of amphetamine or cannabis.
authors: a Kristiina Kivimies, Department of Forensic Psychiatry , University of Eastern Finland, Niuvanniemi Hospital , Kuopio , Finland.
authors: Kristiina
authors: K
authors: Kivimies
authors: b Eila Repo-Tiihonen, Department of Forensic Psychiatry , University of Eastern Finland, Niuvanniemi Hospital , Kuopio , Finland.
authors: Eila
authors: E
authors: Repo-Tiihonen
authors: c Hannu Kautiainen, Helsinki University Central Hospital, Unit of Primary Health Care and University of Helsinki, Department of General Practice , Helsinki , Finland.
authors: Hannu
authors: H
authors: Kautiainen
authors: d Päivi Maaranen, Kuopio University Hospital, Department of Psychiatry , Kuopio , Finland.
authors: Päivi
authors: P
authors: Maaranen
authors: e Leea H. Muhonen, City of Helsinki, Department of Social Services and Health Care , Special Services , Helsinki , Finland.
authors: Leea H
authors: LH
authors: Muhonen
authors: f Martti Heikkinen, Helsinki University Central Hospital, Department of Psychiatry , Jorvi Hospital , Espoo , Finland.
authors: Martti
authors: M
authors: Heikkinen
authors: g Jari Tiihonen, Department of Forensic Psychiatry , University of Eastern Finland, Niuvanniemi Hospital , Kuopio , Finland , Department of Mental Health and Alcohol Research , National Institute for Health and Welfare , Helsinki , Helsinki , Finland and Department of Clinical Neuroscience , Karolinska Institutet , Stockholm , Sweden.
authors: Jari
authors: J
authors: Tiihonen
mesh_terms: D000293:Adolescent; D000328:Adult; D019969:Amphetamine-Related Disorders / Q000453:epidemiology; D005260:Female; D005387:Finland; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology; D009293:Opioid-Related Disorders / Q000453:epidemiology*; D015995:Prevalence; D012189:Retrospective Studies; D012559:Schizophrenia / Q000453:epidemiology*; D055815:Young Adult
keywords: Amphetamine; Cannabis; Hospitalization; Opioid; Schizophrenia