Page 41 - Post-traumatic stress disorder in adults with mild intellectual disability: Screening, assessment, and brief intensive EMDR therapy

Reliability and validity of DITS-ID
for “Stereotyped behavior” .88 (frequency) and .90 (severity), indicating
acceptable to excellent internal consistency.
Impact of Event Scale-Intellectual Disability, (IES – ID)
The IES – ID (Hall et al., 2014) is a self-report screening questionnaire
indexing subjective stress caused by potentially traumatic events. In our
study, we used the Dutch translation of the IES – ID. The IES – ID corresponds
to the three DSM-IV-TR PTSD symptom categories: avoidance, intrusion,
and hyperarousal. The instrument consists of 22 questions scored on a
3-point Likert scale (1 = a little bit, 2 = in the middle, 3 = a lot). No research
has been done on the psychometric characteristics of the Dutch version of
the IES-ID. The English version of the IES-ID has been found to have good to
excellent psychometric properties, including high internal consistency and
test-retest reliability, among individuals with MID-BIF (Hall et al., 2014). In
the present study, Cronbach’s alpha for the IES-ID total score was .94, which
indicates excellent internal consistency.
Anxiety, Depression, and Mood Scale (ADESS)
The ADESS (in Dutch: Angst Depressie en Stemmingsschaal; Anxiety,
Depression and Mood Scale [ADAMS]; Hermans et al., 2008) is a Dutch
questionnaire for measuring symptoms of anxiety and depression in
people with ID according to the DSM-5. This was accomplished by proxy
informants. The ADESS consists of four subscales: “Depressive mood”
(thirteen items), “Fear and tension” (seven items), “Social avoidance” (seven
items) and “Other problems” (eleven items). Each item of the ADESS is
scored on a 4-point Likert scale (0 = never/no problem, 1 = occasional/
minor problem, 2 = regular-moderate problem, 3 = frequent/severe
problem). The ADESS has sufficient to good psychometric properties
(i.e., internal consistency, test-retest reliability, and interrater reliability).
The ADESS showed sufficiently reliability as a screen for anxiety and
depression against the PAS-ADD Interview with (Dutch) adults with ID
(sensitivity between 73% and 88% and specificity range from 71% to 80%;
Hamers et al., 2018; Hermans et al., 2012). In the present study, Cronbach’s
alpha for the ADESS total score was .91, for “Depressive mood” .87, for
“Anxiety and stress” .74, for “Social avoidance” .84 and for “Other problems”
.73, indicating acceptable to excellent internal consistency.
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