Page 69 - Post-traumatic stress disorder in adults with mild intellectual disability: Screening, assessment, and brief intensive EMDR therapy

Development and evaluation of TS-ID
may not be surprising that the TS-ID proxy version did not demonstrate
significant validity in distinguishing individuals with and without a PTSD
diagnosis. This lack of validity underscores the limitations and challenges
of using proxy informants for screening for subjectively experienced
psychological symptoms, such as for PTSD (Webb et al., 2024).
In our study, a large proportion of the participants required assistance in
completing the TS-ID adult version. When assisting persons with MID-BIF
to complete self-reports, the nature of the contact between them and the
diagnostician can be a confounder, especially when sensitive topics are
addressed (Kooijmans et al., 2022). It remains unclear whether the assistance
from the master students and the main researcher has influenced clients’
responses and consequently affected the validity and cut-off value of the
TS-ID adult version. We have taken measures to reduce the influence: (1)
To determine if support was needed, we asked participants, after they had
read the TS-ID adult version instruction or after the instruction had been
read aloud, ‘Can you tell me what to do now?’ rather than ‘Do you know
what to do?’; (2) Pilot testing showed that participants could understand
the content of the questions; however, if not, we only provided instructions
on understanding the question and not on answering it.
Limitations of the study
This study has some limitations that should be considered. First, we
examined a specific sample of adults with MID-BIF living in supported
housing in the Netherlands, which may limit the generalisability of the
findings. Second, PTSD diagnosis was solely based on the DITS-ID rather
than on a comprehensive differential diagnostic assessment. Therefore,
the rate of PTSD in this sample should not be used as a clinical prevalence
estimate. Finally, one of the developers of the TS-ID was also involved in
collecting some of the data, which may have led to bias.
Recommendation for future research
The TS-ID version for adults is a new instrument, and future studies on the
screener should be conducted in various samples and settings, such as
outpatient care settings, forensic care and mental health settings, where
many people with MID-BIF receive care and treatment (Nieuwenhuis et
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