Prevalence of mental illness, substance use disorder, and dual diagnosis among adults in custody

Abstract Background The prevalence of mental illness, substance use disorders, and their dual diagnosis is disproportionately high among people in prisons compared to the community. Accurate prevalence estimates are required to inform resourcing of prison health services and reduce the risk of harm...

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Main Authors: Darcy J. Coulter, Lindsay A. Pearce, Matthew Legge, Jesse T. Young, David B. Preen, Ed Heffernan, Jocelyn Jones, Stuart A. Kinner
Format: Article
Language:English
Published: BMC 2025-08-01
Series:Population Health Metrics
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Online Access:https://doi.org/10.1186/s12963-025-00408-7
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author Darcy J. Coulter
Lindsay A. Pearce
Matthew Legge
Jesse T. Young
David B. Preen
Ed Heffernan
Jocelyn Jones
Stuart A. Kinner
author_facet Darcy J. Coulter
Lindsay A. Pearce
Matthew Legge
Jesse T. Young
David B. Preen
Ed Heffernan
Jocelyn Jones
Stuart A. Kinner
author_sort Darcy J. Coulter
collection DOAJ
description Abstract Background The prevalence of mental illness, substance use disorders, and their dual diagnosis is disproportionately high among people in prisons compared to the community. Accurate prevalence estimates are required to inform resourcing of prison health services and reduce the risk of harm to people experiencing these conditions. Existing estimates, where available, often rely on only one data source. Method We used three data sources – self-reported history of diagnoses, in-prison medical records, and administrative data to estimate the prevalence of mental illness, substance use disorder, and dual diagnosis among two large cohorts of non-Indigenous and Aboriginal and Torres Strait Islander people in Australian prisons. We calculated population-weighted proportions of the samples with each condition. Inter-rater reliability metrics inform data source agreement. Results The prevalence of mental illness only, substance use disorder only, and dual diagnosis was 17.0% (95%CI 12.0–24.5), 14.8% (95%CI 9.6–18.1), and 44.2% (95%CI 33.2–54.7), respectively, for incarcerated, non-Indigenous adults. For incarcerated Aboriginal and Torres Strait Islander adults, our corresponding estimates were 7.0% (95%CI 4.3–11.5), 26.8% (95%CI 18.9–33.5), and 40.9% (95%CI 30.1–48.2). These estimates differed significantly from those derived from singular data sources. Individual data sources’ agreement was weakest for substance use disorder diagnoses and strongest for dual diagnoses. Conclusions Individual data sources likely have high specificity and low sensitivity, thus under-ascertaining diagnoses. We recommend using multiple data sources to estimate prevalence to ensure adequate ascertainment of these conditions among people in prison and to ensure in-prison and transitional health services are appropriately resourced.
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spelling doaj-art-bee04915ff414d408bb2af9990eb6d6d2025-08-20T03:43:25ZengBMCPopulation Health Metrics1478-79542025-08-0123111310.1186/s12963-025-00408-7Prevalence of mental illness, substance use disorder, and dual diagnosis among adults in custodyDarcy J. Coulter0Lindsay A. Pearce1Matthew Legge2Jesse T. Young3David B. Preen4Ed Heffernan5Jocelyn Jones6Stuart A. Kinner7Justice Health Group, enAble Institute, Curtin UniversityJustice Health Group, enAble Institute, Curtin UniversityJustice Health Group, enAble Institute, Curtin UniversitySchool of Population Health, Curtin UniversitySchool of Population and Global Health, The University of Western AustraliaForensic Mental Health Group, Queensland Centre for Mental Health ResearchMaladjiny Research Centre, Kurongkurl Katitjin, Edith Cowan UniversityJustice Health Group, enAble Institute, Curtin UniversityAbstract Background The prevalence of mental illness, substance use disorders, and their dual diagnosis is disproportionately high among people in prisons compared to the community. Accurate prevalence estimates are required to inform resourcing of prison health services and reduce the risk of harm to people experiencing these conditions. Existing estimates, where available, often rely on only one data source. Method We used three data sources – self-reported history of diagnoses, in-prison medical records, and administrative data to estimate the prevalence of mental illness, substance use disorder, and dual diagnosis among two large cohorts of non-Indigenous and Aboriginal and Torres Strait Islander people in Australian prisons. We calculated population-weighted proportions of the samples with each condition. Inter-rater reliability metrics inform data source agreement. Results The prevalence of mental illness only, substance use disorder only, and dual diagnosis was 17.0% (95%CI 12.0–24.5), 14.8% (95%CI 9.6–18.1), and 44.2% (95%CI 33.2–54.7), respectively, for incarcerated, non-Indigenous adults. For incarcerated Aboriginal and Torres Strait Islander adults, our corresponding estimates were 7.0% (95%CI 4.3–11.5), 26.8% (95%CI 18.9–33.5), and 40.9% (95%CI 30.1–48.2). These estimates differed significantly from those derived from singular data sources. Individual data sources’ agreement was weakest for substance use disorder diagnoses and strongest for dual diagnoses. Conclusions Individual data sources likely have high specificity and low sensitivity, thus under-ascertaining diagnoses. We recommend using multiple data sources to estimate prevalence to ensure adequate ascertainment of these conditions among people in prison and to ensure in-prison and transitional health services are appropriately resourced.https://doi.org/10.1186/s12963-025-00408-7Dual diagnosisMental illnessSubstance usePrisonPrevalenceIndigenous
spellingShingle Darcy J. Coulter
Lindsay A. Pearce
Matthew Legge
Jesse T. Young
David B. Preen
Ed Heffernan
Jocelyn Jones
Stuart A. Kinner
Prevalence of mental illness, substance use disorder, and dual diagnosis among adults in custody
Population Health Metrics
Dual diagnosis
Mental illness
Substance use
Prison
Prevalence
Indigenous
title Prevalence of mental illness, substance use disorder, and dual diagnosis among adults in custody
title_full Prevalence of mental illness, substance use disorder, and dual diagnosis among adults in custody
title_fullStr Prevalence of mental illness, substance use disorder, and dual diagnosis among adults in custody
title_full_unstemmed Prevalence of mental illness, substance use disorder, and dual diagnosis among adults in custody
title_short Prevalence of mental illness, substance use disorder, and dual diagnosis among adults in custody
title_sort prevalence of mental illness substance use disorder and dual diagnosis among adults in custody
topic Dual diagnosis
Mental illness
Substance use
Prison
Prevalence
Indigenous
url https://doi.org/10.1186/s12963-025-00408-7
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