Psychiatric diagnosis and differential risks of offending following discharge.

Psychiatric diagnosis is not considered a risk factor for offending following discharge. However, treatment interventions and aftercare are strongly influenced by clinical primary diagnosis. We compared differential risks of reoffending of patients falling into six primary diagnostic categories following discharge from Medium Secure Units in the UK: schizophrenia/schizoaffective disorder; delusional disorder; mania/hypomania; depressive disorder; organic brain syndrome; personality disorder. We followed up 1344 patients, on average 6.2 years (SD=2.1) at risk, discharged from 7 of 14 Regional Medium Secure services in England and Wales. Outcomes were period prevalence, incidence, and cumulative probability of criminal conviction. Established demographic and criminal history predictors of reoffending were observed across different diagnostic categories. Risks of all offending were increased for personality disorder, violence/acquisitive offending for delusional disorder, sexual offending for mania/hypomania and violence/acquisitive offending for organic brain syndrome. Patterns of risk over time differed markedly between categories of mental disorder. Most patients with personality disorder who offended violently did so within 4 years of discharge. A subgroup with delusional disorder demonstrated increased risk of violent offending 5 years after discharge. Differential risks of reoffending are observed between different diagnostic groups. Clinical diagnosis should be included together with established risk measures in risk management following discharge. Close supervision of patients with personality disorder should begin immediately after discharge when risks of reoffending are greatest. For delusional disorder further investigation is needed into the marked increase in risk of violence after 5 years.