The International Trauma Questionnaire: development of a self‐report measure of ICD‐11 PTSD and complex PTSD

Objective:
The 11th version of the International Classification of Diseases (ICD-11) has proposed two related trauma diagnoses: Post-traumatic stress disorder (PTSD) and Complex PTSD (CPTSD). Using a newly developed, disorder-specific measure of PTSD and CPTSD called the International Trauma Questionnaire
(ITQ) the current studywill (i) assess the factorial validity of ICD-11 PTSD and CPTSD; (ii) provide the first test of the discriminant validity of these constructs; and (iii) provide the first comparison of ICD-11, and Diagnostic and
Statistical Manual, Fifth Edition (DSM-5), PTSD diagnostic rates using
disorder-specific measures.
Method:
ICD-11 and DSM-5 PTSD-specific measures were completed
by a British clinical sample of trauma-exposed patients (
N=
171). The
structure and validity of ICD-11 PTSD and CPTSD were assessed by
means of factor analysis and assessing relationships with criterion
variables.
Results:
Diagnostic rates under ICD-11 were significantly lower than
those under DSM-5. A two-factor second-order model reflecting the
distinction between PTSD and CPTSD best represented the data from
the ITQ; and the PTSD and CPTSD factors differentially predicted
multiple psychological variables.
Conclusion:
The factorial and discriminant validity of ICD-11 PTSD
and CPTSD was supported, and ICD-11 produces fewer diagnostic
cases than DSM-5.