Development and evaluation of the Trauma Screener-Intellectual Disability: a post-traumatic stress disorder screening tool for adults with mild intellectual disability or borderline intellectual functioning.

Background: This study aimed to evaluate the validity and reliability of the adult self-report and proxy version of the Trauma Screener-Intellectual Disability (TS-ID) in adults with mild intellectual disability or borderline intellectual functioning (MID-BIF). An optimal cut-off value was determined for the ratio of specificity to sensitivity for predicting the diagnosis of post-traumatic stress disorder (PTSD).

Methods: The TS-ID was adapted from a Dutch Child and Adolescent Trauma Screener, for use with adults with MID-BIF. Outcomes based on the TS-ID were compared with the presence of PTSD, as classified using the Diagnostic Interview Trauma and Stressors-Intellectual Disability (Mevissen et al. 2018). The TS-ID adult version was administered to 97 participants with MID-BIF who lived in supported housing, whereas the TS-ID proxy version was administered to 92 family members or professional caregivers.

Results: The TS-ID adult version showed high internal consistency (Cronbach's α = .94) and excellent validity (AUC = .94) for distinguishing PTSD in adults with MID-BIF. Optimal specificity and sensitivity was found at a cut-off score of 18. Although the TS-ID proxy version demonstrated excellent internal consistency (Cronbach's α = .93), it showed no validity in statistically distinguishing PTSD in adults with MID-BIF.

Conclusions: The TS-ID showed favourable psychometric qualities as a screening instrument of PTSD in the case for people with MID-BIF.