Offending in psychiatric patients after discharge from medium secure units: prospective national cohort study.

The rate of violent offending is low and the strongest association with offending was previous offending. Psychiatric variables were less important, with diagnosis and number of previous admissions showing no significant association. Substance misuse and sexual abuse were associated with increased offending risk, although patients were less likely to be convicted after a lengthy admission or if they had a history of self harm. Patients who lost contact with services were more likely to be convicted but this finding is ambiguous, as the sample included patients found to have no psychiatric diagnosis. It is consistent with the possibility that aftercare is effective in preventing reconviction, and we know that compulsory aftercare in restricted patients is associated with a rate of serious offending below 0.6% a year. Our study cannot establish causal relationships, but it shows that offending is uncommon. The rate of violent offending is so low that there is little scope for overall reduction and it would be better to concentrate on the identification of high risk patients. The American Macarthur study identified the “psychopathy checklist—screening version” (PCL-SV) as the best single predictor of violence in psychiatric patients, and we recommend further exploration of its use in medium security hospitals in England and Wales.