A systematic review of structured group interventions with mentally disordered offenders

Over the last 15 years, rehabilitation of offenders has been rigorously researched, resulting in new knowledge and understanding about factors decreasing recidivism amongst them. Typically, such interventions have been based on cognitive behavioural therapy. However, until recently, little research had been carried out on the rehabilitation of offenders with mental disorder. The authors present the first systematic review of the efficacy of structured group interventions with mentally disordered offenders.

To evaluate structured group interventions with mentally disordered offenders through systematic review of the evidence for their efficacy and effectiveness.

A standardized search strategy, with complementary methods of data retrieval to ensure a high degree of recall, was employed. Meta-analysis was not undertaken due to sample heterogeneity and lack of comparable data. Instead, effect sizes were calculated on all papers with sufficient data. Pooled effect sizes were calculated for groups of interventions with a similar focus.

Twenty studies were retrieved that fitted the inclusion criteria. It was possible to categorize these, predominantly British, studies into four main themes: problem-solving; anger/aggression management; self-harm; and other. The mean pooled effect sizes for the first two groups were suggestive of a moderate to high effect, but methodological variation means that these findings should still be treated as preliminary.

Calculated effect sizes give optimism for the efficacy of structured group interventions with mentally disordered offenders. It is important now that more rigorous and consistent research methods be applied, even in secure hospital environments. Some suggestions towards achieving this are offered, drawing from the work to date, inclusive of the need for agreement on common outcome measures and development of networks to improve sample sizes.