The most robust evaluation of the Sex Offender Treatment Programme (SOTP) in England and Wales (Home Office, 2003) examined the impact of the prison-based programme. This compared two-year reconviction rates for prisoners who participated in the programme with those who did not.
Findings indicated that the SOTP had an impact on reconvictions for sexual and/or violent offences (as a combined measure). An explanation for this effect could be that a proportion of violent reconvictions were sexually motivated offences. Sexual reconvictions were combined with those for violent offences because sexual offenders (in the absence of intervention) are reconvicted for sexual offences at a very low rate—less than 5 per cent. over two years. Any decrease in this rate as a result of treatment is therefore unlikely to be statistically significant.
For combined sexual and violent reconviction, the treatment group showed a statistically significantly lower rate of reconviction overall than the comparison group (4.6 per cent. and 8.1 per cent. respectively, see Table 4 in Home Office Research Findings No. 205). Treatment participants in the medium-low and medium-high risk groups showed a statistically significantly lower rate of reconviction than respective risk groups in the comparison sample (see Table 4 in HORF 205).
For general and sexual reconviction rates, the treatment group showed lower rates of reconviction than the comparison group although differences were not statistically significant (see Tables 5 and 3 respectively in HORF 205). No statistically significant differences were found among risk groups.
These findings relate to offenders who completed the SOTP between 1992 and 1994. A programme of research is planned to examine the impact of the prison-based SOTP delivered to offenders post-1994 in terms of both short-term change in relation to treatment targets (e.g. victim empathy) and longer-term change in terms of future re-offending.
The National Offender Management Service has set up a standing group to take forward work on a treatment strategy for sex offenders to ensure that effective treatment is delivered to sex offenders in custody and the community as part of a broader package of interventions and management controls to reduce the risk of re-offending. As part of this work provision for sex offenders in custody will be considered.