Purpose
For the 3.8 per cent of people with intellectual disabilities (IDs) who have offended sexually, the main form of treatment is the group-based, cognitive-behavioural, adapted sex offender treatment programme (ASOTP) that focusses on challenging cognitive distortions condoning sex offending. The purpose of this paper is to provide an evaluation of how effective the ASOTP is at reducing ID sex offenders’ cognitive distortions.
Design/methodology/approach
Three databases were searched systematically: PsycINFO, MEDLINE and Web of Science. Six studies met the inclusion criteria, yielding 118 participants. Using a random-effects model, effect sizes were calculated using pre- and post-treatment scores on a measure of cognitive distortions. The standardised mean difference (SMD) was 1.77 (95 per cent CI: 1.06, 2.46), which was statistically significant (p<0.001) and “large”. Sensitivity analysis demonstrated that this SMD was robust, and a check for publication bias revealed that it was unlikely that the “file drawer problem” confounded the meta-analysis.
Findings
These results indicated that the ASOTP can significantly reduce ID sex offenders’ cognitive distortions, regardless of treatment length, IQ level, language abilities, or offence type. Consistent with earlier reports, longer treatment resulted in the greatest reductions: the optimum treatment length was 24 months.
Research limitations/implications
The ASOTP’s current evidence is comprised wholly of case and quasi-experimental studies, none of which employed control groups. This paper highlights how there is a dire need for high-quality experimental evaluation of the ASOTP.
Practical implications
Clinicians are advised to continue using the ASOTP as the main treatment for ID sex offenders until the effectiveness of the ASOTP is further examined using randomised controlled trials.
Originality/value
This is the first meta-analytic review of the effectiveness of the ASOTP.
Establishing a sex offender treatment programme within a prison
