Actuarial prediction of violent recidivism in mentally disordered offenders

• Published in: Psychological medicine 2007-11, Vol.37 (11), p.1539-1549
• Main Authors: SNOWDEN, ROBERT J., GRAY, NICOLA S., TAYLOR, JOHN, MacCULLOCH, MALCOLM J.
• Format: Article
• Language: English
• Subjects: Actuarial Analysis; Adolescent; Adult; Aged; Biological and medical sciences; Crime - psychology; Crime - statistics & numerical data; Follow-Up Studies; Forensic Psychiatry - instrumentation; Habitual offenders; Humans; Male; Medical sciences; Mental disorders; Mental Disorders - complications; Mental Disorders - psychology; Mental health; Middle Aged; Predictive Value of Tests; Psychology. Psychoanalysis. Psychiatry; Psychometrics - instrumentation; Psychometrics. Diagnostic aid systems; Psychopathology; Psychopathology. Psychiatry; Recidivism; Risk assessment; Risk Assessment - methods; Sex Offenses - psychology; Sex Offenses - statistics & numerical data; Techniques and methods; Violence; Violence - psychology; Violence - statistics & numerical data
• ISSN: 0033-2917; 1469-8978
• DOI: 10.1017/S0033291707000876

Actuarial instruments may be useful in predicting long-term violence in mentally disordered patients. We compared two instruments that differ in terms of what they are designed to predict (general versus violent recividism) and the inclusion of stable mental health variables. A large sample of mentally disordered patients were scored on two risk assessment instruments, the Violence Risk Appraisal Guide (VRAG) and the Offender Group Reconviction Scale (OGRS), based on information at the point of discharge. Their criminal histories for at least 2 years following discharge were obtained from official records. Both instruments were good predictors of both violent and general offending. Over shorter periods (0.85], which were significantly better than the OGRS. For longer follow-up periods the instruments had approximately equal prediction accuracy. However, both instruments predicted far more offences than were in fact recorded. The VRAG is a very good predictor of future violence in the UK sample. The OGRS may also be of value as it can be completed quickly and without the need for mental health variables. Caution is needed, however, as both instruments appeared to over-predict the levels of reconvictions in this sample.