The predictive validity of common risk assessment tools in men with intellectual disabilities and problematic sexual behaviors

• We test three common risk assessment tools on men with intellectual disabilities (ID).
• We measure behavioural outcomes (legal and illegal).
• All risk assessment tools used were effective at predicting at least one type of recidivism.
• Risk tools used for men with ID need to account for special circumstances.

This CIHR-funded study examined whether certain current risk assessment tools were effective in appraising risk of recidivism in a sample of sex offenders with intellectual disabilities (ID). Fifty men with ID who had engaged in problematic sexual behavior (PSB) were followed for an average of 2.5 years. Recidivism was defined and measured as any illegal or problematic behavior, as well as any problematic but not necessarily illegal behavior. At the beginning of the study, each participant was rated on two risk assessment tools: the Violence Risk Appraisal Guide (VRAG) and the Sex Offender Risk Appraisal Guide (SORAG). During each month of follow-up, participants were also rated on the Short-Dynamic Risk Scale (SDRS), an assessment tool intended to measure the risk of future problematic behaviors. Data was analyzed using t-tests, Cohen’s d and area under the curve (AUC) to test predictive validity of the assessment tools. Using the AUC, results showed that the VRAG was predictive of sexual (AUC = 0.74), sexual and/or violent (AUC = 0.71) and of any criminally chargeable event (AUC = 0.69). The SORAG was only significantly predictive of sexual events (AUC = 0.70) and the SDRS was predictive of violent events (AUC = 0.71). The t-test and Cohen’s d analyses, which are less robust to deviations from the assumptions of normal and continuous distribution than AUC, did not yield significant results in each category, and therefore, while the results of this study suggest that the VRAG and the SORAG may be effective tools in measuring the short term risk of sexual recidivism; and the VRAG and SDRS may be effective tools in appraising long term risk of sexual and/or violent recidivism in this population, it should be used with caution. Regardless of the assessment tool used, risk assessments should take into account the differences between sex offenders with and without ID to ensure effective measurement.