title: Measuring symptoms of post-traumatic stress disorder in people with intellectual disabilities: the development and psychometric properties of the Impact of Event Scale-Intellectual Disabilities (IES-IDs).
abstract: BACKGROUND
  The aims of the study were to (1) revise the Impact of Event Scale-Revised for use with people with intellectual disabilities (IDs), creating the Impact of Event Scale-Intellectual Disabilities (IES-IDs), (2) assess the reliability of the IES-IDs, and (3) compare the IES-IDs to an existing measure trauma-related symptomatology, namely the Lancaster and Northgate Trauma Scale (LANTS), along with measures of anxiety and depression.
  
  
  METHODS
  Forty adults with IDs who had experienced at least one traumatic event were recruited and completed the IES-IDs and the LANTS on two occasions, separated by 2 weeks. Participants also completed the Glasgow Depression Scale and the Glasgow Anxiety Scale, along with the Trauma Information Form which was used to collect information about trauma history.
  
  
  RESULTS
  Fifteen per cent of the sample had encountered five or more traumatic events. The IES-IDs and the LANTS had good to excellent internal consistency and test-retest reliability. Both measures correlated with self-report measures of depression and anxiety, although the strength of this correlation was greater with the LANTS. There was a significant positive correlation between trauma frequency and the IES-IDs, while trauma frequency did not correlate with the LANTS.
  
  
  CONCLUSIONS
  Both the IES-IDs and the LANTS appear to have good reliability.
  
  
  CONCLUSIONS
  There is a lack of well-developed questionnaires that can be used to assess symptoms of post-traumatic stress disorder (PTSD) in people with intellectual disabilities. The Impact of Event Scale-Revised was augmented creating the Impact of Event Scale-Intellectual Disabilities (IES-IDs). The IES-IDs was shown to have good psychometric properties. The IES-IDs was compared to the Lancaster and Northgate Trauma Scale (LANTS), but the LANTS did not correlate with trauma frequency. However, this study had a small sample size, and a much larger study is needed to examine the factor structure of both the IES-IDs and the LANTS. Future studies should attempt to recruit people with IDs who have a diagnosis of PTSD.
authors.affiliation: Department of Psychological Sciences, Norwich Medical School, University of East Anglia, Norwich, UK.
authors.forename: James C
authors.initials: JC
authors.lastname: Hall
authors.forename: Laura
authors.initials: L
authors.lastname: Jobson
authors.forename: Peter E
authors.initials: PE
authors.lastname: Langdon
mesh_terms: D000328:Adult; D001007:Anxiety / Q000175:diagnosis*; D003863:Depression / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D015203:Reproducibility of Results; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis*; D055815:Young Adult
keywords: IES-IDs; Impact of Event Scale-Intellectual Disabilities; LANTS; Trauma Information Form; anxiety disorders; assessment; learning disabilities; neurodevelopmental disorders; post-traumatic stress disorder; trauma