Profiling Mentally Ill Offenders in Hong Kong: a 5-year Retrospective Review Study

This study aimed to determine the prevalence of mental illness in offenders referred to psychiatrists from January 2011 to March 2016 and any associations between crime and mental illness in these offenders.

Case notes of offenders referred to psychiatrists at the Siu Lam Psychiatric Centre from 1 January 2011 to 31 March 2016 were reviewed. Data on sex, age on admission, educational level, principal psychiatric diagnosis, index offence, source and reason of referral, and outcome were collected.

Case notes were reviewed for 4492 offenders (75% males) aged 14 to 93 (mean, 40.6) years. Of these, 68% were referred by the courts for psychiatric report and 32% were referred by correctional institutions for psychiatric assessment and treatment. Approximately 73% of them had a diagnosable mental disorder. The most common principal psychiatric diagnoses were schizophrenia and related disorders (25%), mental and behavioural disorders due to psychoactive substance use (20%), and mood disorders (9%). The most common index offences were theft and related offences (22%), acts intended to cause injury (20%), and illicit drug offences (11%). Offences involving violence were more prevalent in males than in females (p < 0.001). In terms of the three most common principal psychiatric diagnoses, 'acts intended to cause injury' was most prevalent in those with 'schizophrenia and other related disorders' than in those with the other two diagnoses (31% vs 19% vs 17%, p < 0.001). 'Theft and related offences' was most prevalent in those with mood disorders than in those with other two diagnoses (38% vs 20% vs 18%, p < 0.001). 'Illicit drug offences' was most prevalent in those with 'mental and behavioural disorders due to psychoactive substance' than those with other two diagnoses (22% vs 8% vs 6%, p < 0.001).

The prevalence of mental disorders among offenders referred to psychiatrists is high. The pattern of associations between crime and mental disorders in these offenders is comparable with that reported in overseas studies. As Siu Lam Psychiatric Centre is the only facility in Hong Kong for mentally ill offenders, our sample is representative, and our results provide cross-sectional pattern of forensic psychiatric service utilisation in Hong Kong.