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.