Page 84 - Post-traumatic stress disorder in adults with mild intellectual disability: Screening, assessment, and brief intensive EMDR therapy

Chapter 4
Table 3. Descriptive Statistics
Outcome n M Note. n = total number of measurements.
SD
PTSD symptoms (TS-ID) 257 25.67 15.98
Adaptive behaviour (GAS) 1164 6.08 77.28
Behavioural problems (BPI) - frequency 152 12.46 11.43
Behavioural problems (BPI) - severity 149 11.51 12.00
Primary outcome measures
PTSD symptoms
The symptom section of the self-report measure Trauma Screener –
Intellectual Disability (TS-ID; Versluis et al., 2025) was used to assess PTSD
symptoms. This section consists of 20 questions scored on a 4-point Likert
scale (0 = never, 1 = sometimes, 2 = often, 3 = almost always). The total
symptom frequency score (range 0-60) was obtained by summing the
scores of the 20 questions, in which questions 9, 10, and 15 were divided
into several sub-questions. For the latter questions, only the highest score
was recorded in the final score. Higher scores indicate greater levels of
PTSD symptoms. The TS-ID has good psychometric properties, including
high internal consistency and excellent validity for distinguishing PTSD
in adults with MID-BIF based on the outcomes of the DITS-ID (Versluis et
al., 2024). Participants completed the symptom questions of the TS-ID, with
the DITS-ID timeline (see DITS-ID) placed next to the TS-ID, which provided
a clear visual cue for the (traumatic and stressful) events. A professional
caregiver was present to explain the items of the TS-ID if needed.
DSM-5-TR PTSD diagnostic status
PTSD diagnostic status was assessed using the Diagnostic Interview Trauma
and Stressors – Intellectual Disability – Adult Version (DITS-ID; Mevissen
et al., 2018). This clinical interview takes approximately 45–60 minutes to
complete and is used to classify DSM-5-TR PTSD. The first section consists
of 31 questions (yes/no/other) regarding Type A and stressful life events
(not meeting the A-criterion but are experienced negatively by the person).
The symptom section includes 39 PTSD symptom questions (PTSD criteria
B, C, D, and E) and four questions on potential atypical trauma symptoms
(yes/no/other). Subsequently, a thermometer card is used to support the
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