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

Medium secure units admit patients for the assessment and treatment of mental disorder associated with risk. We investigated how many patients offend after discharge.

Participants, methods, and results

We collected demographic and clinical data on all 959 patients discharged from medium secure units in England and Wales between 1 April 1997 and 31 March 1998 and used the offenders' index to find details of subsequent convictions.

A total of 145 patients (15%) were convicted within two years, including 60 (6%) who were convicted of violent offences (table).

Table 1.

Risk factors for conviction over two years for patients discharged from medium secure units in England and Wales (n=959)

Variable	Total	No convicted	Odds ratio*(95% CI)
Sex:
Male	843	135	1
Female	116	10	1.20 (0.5 to 2.87)
Ethnic group:
White	674	94	1
Black	204	37	1.69 (0.94 to 3.02)
Other	81	14	1.72 (0.80 to 3.66)
Length of stay:
≤540 days (75th centile)	719	131	1
>540 days	240	14	0.37 (0.17 to 0.78)
History of self harm:
No	525	94	1
Yes	397	43	0.48 (0.29 to 0.78)
History of alcohol or drug problem:
No	348	24	1
Yes	584	118	2.20 (1.27 to 3.81)
History of sexual abuse:
No	788	112	1
Yes	134	21	2.13 (1.06 to 4.30)
Index offence:
None	148	15	1
Violent	419	53	0.42 (0.17 to 1.00)
Property	147	49	0.95 (0.36 to 2.48)
Sexual	71	8	0.31 (0.09 to 1.08)
Other	167	19	0.19 (0.07 to 0.55)
Previous convictions:
0	251	7	1
1	71	9	3.60 (1.28 to 10.30)
2-5	242	35	3.44 (1.47 to 8.01)
6-10	134	25	3.68 (1.41 to 9.63)
>10	213	64	6.83 (2.66 to 17.53)
Lost contact with services:
No	800	105	1
Yes	143	40	2.16 (1.22 to 3.81)

^*Odds ratios of conviction over two years are adjusted for all other variables included in the model.

Comment

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.

What is already known on this topic

Offending by psychiatric patients is of great public concern

What this study adds

In the two years after discharge from medium security, only 6% of patients commit a violent offence and the strongest association with reoffending is previous offending

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.¹

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 study² identified the “psychopathy checklist—screening version” (PCL-SV)³ 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.