Participants and Procedure

The sample consisted of 347 forensic psychiatric patients who were unconditionally released between 2004 and 2008 from any of the 12 Dutch FPCs. ¹ Of these 347 patients, 317 were male and 30 were female. Given the low number of female patients and the fact that the HKT-R has not been validated for female offenders (Spreen et al., 2014), we decided to exclude them from this study. Information was collected for all participants on demographic characteristics, psychiatric disorders according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev. [DSM-IV-TR]; APA, 2000), intellectual ability, and criminal records through electronic patient files. In addition, 20 trained coders assessed the HKT-R using information from the patients’ criminal files, with detailed descriptions of their background and criminal history, psychiatric evaluation reports, treatment plans, leave requests, and prolongation advice. Bogaerts et al. (2018) assessed the interrater reliability in a sample of 347 patients who were discharged between 2004 and 2008 from the 12 FPCs, by calculating the intraclass correlation coefficient (ICC). The Clinical domain had good interrater reliability with the ICC being .85 with a 95% confidence interval ranging from .67 to .94. This study used scores at the time of unconditional release as offenders are at that moment considered as having a low enough risk for recidivism to enter society and are no longer supervised by correctional services (Van der Linde et al., 2020). All data were anonymized before running analyses. In this study, patients were not able to give informed consent because many of them no longer reside in the institutions and a number of them have already died. However, in exceptional cases, like in this one, research with patient file data is possible without permission (Article 7:458 paragraph 3 of the Dutch Civil Code [in Dutch: BW]). Furthermore, this research serves the public interest, namely the safety of society and the study with this large group of patients cannot be performed in any other way (as mentioned in Uitzondering op toestemmingsvereiste [Exception to consent requirement; Art. 7: 458 BW]). The study was approved by the ethical review board of Tilburg University School of Social and Behavioral Sciences and preregistered at AsPredicted. ²