Page 63 - Post-traumatic stress disorder in adults with mild intellectual disability: Screening, assessment, and brief intensive EMDR therapy

Development and evaluation of TS-ID
criteria. The protocol systematically evaluates DSM-criteria A, B, C, D, E, F,
G and H to determine whether an individual meets the criteria necessary
for PTSD diagnosis. The DITS-ID was developed for people with MID-BIF.
To facilitate accessibility, DITS-ID employs simplified language and visual
cues. DITS-ID consists of five sections. The first section consists of 31
questions on whether the participant had ever been exposed to a certain
event. If the answer is ‘Yes’, the interviewer asks ‘What happened?’ and
maps an event on a timeline. According to the answer, the interviewer
determines whether the event meets the A criterion of PTSD. The following
section includes 39 questions on PTSD symptoms, 32 of which correspond
to the DSM-5 symptom list (PTSD criteria B, C, D and E). In addition, four
potentially atypical symptoms (e.g. ‘Have you changed in terms of food
since the events?’. For example, that you eat too much or too little?) are
asked. Participants are requested to answer with ‘Yes’ or ‘No’, while the
‘Other’ category allows for answers such as ‘I don’t know’ or ‘I’ve always had
that’. Then a thermometer chart, which serves as a visual analogue, helps
participants to indicate the subjective degree of impairment in daily life on
a scale from 0 (totally not) to 8 (very much); a score of 4 or higher indicates
that the G criterion is met. If the G criterion is met, the participant is asked
to provide details about when the symptoms started, at what age and after
what event. This helps confirm whether the symptoms persist for more
than a month, which is a prerequisite for diagnosing PTSD (criterion F).
Finally, the interviewer assesses whether the symptoms can be attributed
to medication, drug use, other medical conditions or mental disorders
(criterion H). The DITS-ID has demonstrated good psychometric properties
in adults with MID-BIF. Internal consistency was high, interrater reliability
of the DITS-ID was good to excellent, and the construct and convergent
validity of the DITS-ID was good (Mevissen et al., 2020; Versluis et al., 2024).
In the present study, Cronbach’s alpha for the DITS-ID total score on the
symptom section (sum of ‘Yes’ scores) was .86, which indicates good
internal consistency.
Procedure
The data were collected between November 2021 and June 2022. Trained
master students of Radboud University and Vrije University Amsterdam,
and the first author administered the TS-ID adult and the DITS-ID to
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