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Self-harm before and during imprisonment: cohort study of males in prison linking population-based routinely collected data in Wales

Marcos del Pozo Banos Orcid Logo, Mark Atkinson Orcid Logo, Sze Chim Lee Orcid Logo, Ann John Orcid Logo

BJPsych Open, Volume: 12, Issue: 1, Start page: e10

Swansea University Authors: Marcos del Pozo Banos Orcid Logo, Mark Atkinson Orcid Logo, Sze Chim Lee Orcid Logo, Ann John Orcid Logo

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DOI (Published version): 10.1192/bjo.2025.10898

Abstract

Background: Self-harm among UK prisoners has risen over the past decade. Aims: To explore self-harm risk factors and mental health conditions in prisoners, pre- and during imprisonment, compared with the general population. Method: This retrospective cohort study linked electronic health records and...

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Published in: BJPsych Open
ISSN: 2056-4724
Published: Cambridge University Press (CUP) 2026
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa70702
Abstract: Background: Self-harm among UK prisoners has risen over the past decade. Aims: To explore self-harm risk factors and mental health conditions in prisoners, pre- and during imprisonment, compared with the general population. Method: This retrospective cohort study linked electronic health records and Ministry of Justice data for Welsh male prisoners (2019), and a comparison general population cohort. We examined imprisonment likelihood based on prior self-harm and mental health conditions using logistic regression. We also studied self-harm risk up to three years during imprisonment through Generalised Estimating Equations and time-stratified Cox regression, using a pre-imprisonment comparator (3 years before). Results: Prisoners (N = 6095) had higher rates of self-harm and mental health conditions pre-imprisonment compared with non-prisoners (e.g. self-harm odds ratio: 2.1 (1.9, 2.2)). Self-harm risk was 5.25–6.47 times higher in prisoners than non-prisoners, both pre- and during imprisonment. Risk was highest shortly after incarceration, then declined, becoming lower than pre-imprisonment after 7 months. While most conditions correlated with higher self-harm risk during imprisonment (e.g. drug use, hazard ratios: 1.5–3.0), some (e.g. depression and alcohol use) showed weaker links in prisoners than non-prisoners, particularly from 7 months after imprisonment. Self-harm risk was seemingly higher in prisoners on remand compared with those sentenced. Conclusions: Pre-imprisonment, self-harm in male prisoners is already high compared with the general population, potentially driving a saturation effect, where known general population risk factors have a weaker effect in prisoners. Self-harm prevention should target people in contact with criminal justice, irrespective of imprisonment. In prisons, prevention efforts deployed at inception should target those with prior self-harm, drug use, learning difficulties, bipolar disorder and those on remand.
Keywords: Data linkage, mental health, prisoners, routinely collected data, self-harm
College: Faculty of Medicine, Health and Life Sciences
Funders: This study has been carried out as part of the Administrative Data Research (ADR) Wales programme of work. ADR Wales is part of the Economic and Social Research Council (part of UK Research and Innovation)-funded ADR UK (grant ES/S007393/1). A.J. and M.D.P.-B. were also funded by the Medical Research Council and Health Data Research UK (Grant DATAMIND: Data Hub for Mental Health Informatics Research Development, with Ref.: MR/W014386/1) and by Health and Care Research Wales (Grant NCSSHP: National Centre for Suicide and Self-Harm Prevention).
Issue: 1
Start Page: e10