Leaves are an essential part of treatment within forensic mental health services, with the goal of a gradual and safe return to society. However, such leaves may lead to public safety concerns. The present retrospective observational cross-sectional study examined patterns in evaluations of leave applications to the Dutch Advisory Board on Review of Leave and how often forensic psychiatric patients do not return from their leave (on time) and how often they commit an offence during this unauthorized absence. We also investigated whether certain patient or offence characteristics can predict unauthorized absences. We found that 375 (2.5%) of the 15,050 granted applications for leave of forensic psychiatric patients with a mandatory treatment order between 2009 and 2020 involved an unauthorized absence, and 23 (0.15%) involved an unauthorized absence with recidivism. Patients with a Cluster B personality disorder, substance use disorder, mood disorder, Psychopathy Checklist-Revised score above 26, arson or violent offence as index offence had a significantly higher chance of unauthorized absences. The standardly coded risk factors, Substance use during treatment and Breaching conditions about treatment and super vision, were also related to a higher chance of unauthorized absences. Patients with a Cluster C personality disorder, paraphilic disorder or sexual offence with a minor or homicide as index offence had a significantly lower chance of unauthorized absences. However, all these associations were very weak. Concluding, unauthorized absences are rare in the Netherlands, and although some patient and offence characteristics were associated with these absences, this relationship is weak, and predicting unauthorized absences is difficult.
