Costs and outcomes of an intervention programme for offenders with personality disorders

The dangerous severe personality disorder programme was developed in high secure prisons and hospitals at great expense to identify and treat the most dangerous offenders with personality disorders.

To evaluate whether the long-term costs of the programme are greater or less than the long-term outcomes.

We used a Markov decision model with a cost-effectiveness analysis to determine the incremental cost of the programme per serious offence prevented and a cost-offset analysis to consider whether monetary benefits were greater than costs.

Costs were consistently higher for the intervention programme and the cost per serious offence prevented was over £2 million, although there was some evidence that adjustments to the programme could lead to similar interventions becoming cost-effective.

Little evidence was found to support the cost-effectiveness of the intervention programme for offenders with personality disorders, although delivery of the programme in a lower-cost prison would probably yield greater benefits than costs. There are frequent calls for mentally disordered offenders to be detained in secure hospitals rather than prisons; however, if reoffending remains the outcome of interest for policy makers, it is likely that the costs of detention in hospital will remain greater than the benefits for dangerous offenders with a personality disorder.