title: Stimulant use disorders in people with psychosis: a meta-analysis of rate and factors affecting variation.
abstract: OBJECTIVE
  Stimulant abuse and dependence often complicate the care of people with psychotic disorders. This study systematically reviews the prevalence estimates reported for stimulant abuse and dependence in people with psychotic disorders, and examines personal, clinical, regional and methodological factors which explain variation in these rates.
  
  
  METHODS
  PsychINFO, EMBASE and MEDLINE (1946-2013) were searched systematically for studies reporting on stimulant drug use disorders in representative samples of people with psychotic disorders. Random effects models estimated the pooled rate of a stimulant use disorder, defined to include stimulant abuse and stimulant dependence. Study characteristics associated with heterogeneity in rates of stimulant use disorder were examined by subgroup analyses for categorical variables, by meta-regression for continuous independent variables and by multiple meta-regression.
  
  
  RESULTS
  Sixty-four studies provided 68 estimates of lifetime or recent stimulant use disorders in 22,500 people with psychosis. The pooled rate of stimulant use disorder was 8.9% (95% CI 7.4%, 10.5%). Higher rates of stimulant use disorders were reported in studies of affective psychosis, studies from inpatient settings, studies from the USA and Australia, and studies with higher rates of cannabis disorder; in multiple meta-regression analysis these factors explained 68% of between-study variance. Rates of stimulant use disorder were stable over time, and unrelated to age, sex, stage of psychosis, type of stimulant drug or study methodology factors.
  
  
  CONCLUSIONS
  Reported rates of stimulant use disorder in people with psychosis are much higher than in the general population but vary widely and are associated with regional, service setting and clinical differences between studies. It is likely that stimulants contribute to the overall burden of psychosis, and that social and environmental factors combine with drug and illness-related factors to influence stimulant use in psychosis.
authors.affiliation: InforMH, Mental Health and Drug and Alcohol Office, NSW Health, North Sydney, Australia School of Population Health, University of Queensland, Brisbane, Australia Grant.Sara@health.nsw.gov.au.
authors.forename: Grant E
authors.initials: GE
authors.lastname: Sara
authors.affiliation: Mental Health Service, Prince of Wales Hospital, Randwick, Australia School of Psychiatry, University of New South Wales, Randwick, Australia.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Large
authors.affiliation: Schizophrenia Research Institute, Darlinghurst, Australia.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Matheson
authors.affiliation: School of Population Health, University of Queensland, Brisbane, Australia.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Burgess
authors.affiliation: Discipline of Psychiatry, Sydney Medical School, University of Sydney, Sydney, Australia CADE Clinic, Department of Academic Psychiatry, Royal North Shore Hospital, Sydney, Australia.
authors.forename: Gin S
authors.initials: GS
authors.lastname: Malhi
authors.affiliation: School of Population Health, University of Queensland, Brisbane, Australia Queensland Centre for Mental Health Research, University of Queensland, Brisbane, Australia.
authors.forename: Harvey A
authors.initials: HA
authors.lastname: Whiteford
authors.affiliation: Centre for Youth Substance Abuse Research, University of Queensland, Brisbane, Australia.
authors.forename: Wayne D
authors.initials: WD
authors.lastname: Hall
mesh_terms: D000697:Central Nervous System Stimulants; D015897:Comorbidity; D006801:Humans; D011618:Psychotic Disorders / Q000453:epidemiology*; D019966:Substance-Related Disorders / Q000453:epidemiology*
chemical_list: D000697:Central Nervous System Stimulants
keywords: affective psychosis; amphetamine; cocaine; ecstasy; schizophrenia; systematic review