Assessing the risk of self-harm in an adult offender population: an incidence cohort study

Self-harm is common among prisoners, particularly female prisoners. In 2007, concerned about the rising incidence, the prison service introduced a care-planning system called Assessment, Care in Custody, and Teamwork (ACCT). To date, it does not incorporate a standardised diagnostic test to estimate the risk of future self-harm. To identify potential screening instruments, or items from those instruments, to predict the risk of self-harm among prisoners. Prisoners who had been assigned to an ACCT during the recruitment period. A multistage prospective cohort study. Following a pilot study, instruments were administered to prisoners by interview at baseline, and followed up for 6 months (or until point of release if this was sooner) to ascertain self-harm status. Instruments were assessed for unidimensionality, scalability (Mokken) and quantitative structure (Rasch). Area under the curve (AUC) analysis was used to examine the ability of instruments and/or their items to predict future self-harm. Cox proportional hazards regression models were used to examine the multivariate predictive ability of the scales and various sociodemographic and sentencing factors. Three prisons (including one women's prison) in northern England. A set of standardised questionnaires, including the Prison Screening Questionnaire (PriSnQuest), Revised Borderline Symptom List-23 (frequency-based responses) (BSL-23-F), Self-Harm Inventory (SHI), Patient Health Questionnaire (PHQ-9) and the Clinical Outcomes in Routine Evaluation - Outcome Measure (CORE-OM), together with sociodemographic and sentencing data. In total, 450 prisoners consented to participate in the study, of whom 26% were female. The mean age of participants was 31.2 years. Over half of male prisoners recruited were on remand, compared with just over one-fifth (22.6%) of female prisoners. The average tariff of those sentenced was 41 months, of which 14.7 months, on average, had been served. Just over one-third of ACCTs had been initiated because of a known self-harm event, and over one-quarter (27.8%) of participants self-harmed during the follow-up period. Thus, almost half (46.7%) of those entered into the study were reported to have self-harmed, either from their index ACCT, or subsequently, or both. Cutting was the most frequent behaviour (51%). All screening instruments showed some evidence of unidimensionality, and four out of five showed scaling criteria consistent with ordinal scaling, so verifying the validity