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IIR 09-342 – HSR&D Study

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IIR 09-342
Developing A Computer-Adapted Test for PTSD
Susan V. Eisen PhD BA
Edith Nourse Rogers Memorial Veterans Hospital, Bedford, MA
Bedford, MA
Funding Period: October 2010 - September 2013

BACKGROUND/RATIONALE:
PTSD is a major concern for veterans, especially now with thousands of veterans returning from deployment in Iraq and Afghanistan. Identification and early treatment of PTSD can prevent it from becoming a chronic condition accompanied by serious impairment in functioning. Consequently, it is important for the VHA to be able to identify veterans who need treatment for PTSD as well as evaluate treatment outcomes. A wide range of PTSD screening and assessment measures are available, but results vary depending on which measure is used. Most of them follow the 17 diagnostic criteria described in the DSM-IV diagnostic manual for psychiatric disorders, although many other items that are not specific to PTSD are also included in existing instruments. Creation, testing and implementation of a Computer-Adapted Test (CAT) for PTSD will identify the most sensitive and discriminating items from among dozens of items on existing measures, allowing for reliable and valid assessment of both presence and severity of PTSD with very few items. The PTSD CAT (P-CAT) we developed for this project goes beyond existing approaches to PTSD assessment by adding items reflective of additional PTSD subdomains identified in the self-report assessment literature and confirmed by our preliminary research in which veterans identified areas they felt were important for assessing PTSD, but which are not among the current diagnostic criteria. The P-CAT also includes domains identified by the new PTSD diagnostic criteria established for DSM-V.

OBJECTIVE(S):
Objectives were to: 1) create and test a PTSD CAT that will be useful for assessing the presence and severity of PTSD symptoms at a given point in time following traumatic exposure, and longitudinally over time to monitor course and/or outcomes of treatment; 2) develop a static, short-form PTSD assessment instrument composed of the most discriminating and informative items for use in situations where computer administration is not practical; 3) validate both the CAT and short forms using three other widely used paper and pencil self-report measures of PTSD severity as well as clinical diagnoses; and 4) assess sensitivity to change over time for both versions of the instrument.

METHODS:
In Phase 1 of the study we administered 89 PTSD self-report questions to a sample of 1,000 veterans, stratified by age/cohort (Vietnam, OEF/OIF) and gender. The 89 items were previously developed or extracted from a total of 893 items from existing PTSD measures. Development of this item bank was done under an earlier HSR&D pilot study. A 2-parameter graded response Item Response Theory (IRT) Model was used to calibrate the PTSD items for incorporation into the CAT. Tests of unidimensionality were done to determine whether the PTSD CAT is essentially unidimensional or multi-dimensional. Tests of differential item functioning were performed to determine whether given the same level of PTSD severity, item responses differed as a function of age or gender. In Phase 2 of the study the PTSD CAT and a 10-item short from were administered to 202 veterans at the Bedford and Boston VAMC's along with three existing PTSD measures, as well as against a clinical diagnosis of PTSD.

FINDINGS/RESULTS:
A sample of over 1,100 veterans was obtained for the Phase 1 item calibration in which respondents rated their symptom severity on each of the 89 items in the item pool. Factor analytic work on the item bank suggested that a bi-factor model with one general PTSD factor and four sub-factors (intrusion/re-experiencing, avoidance, negative mood and cognition, and hyperarousal) yields good model fit. The four sub-factors are consistent with proposed DSM-5 criteria for PTSD. Differential item functioning (DIF) analysis by age and gender suggests only one item (I enjoyed taking risks) with gender DIF. There were no items showing DIF by age. Both a computer adapted test (CAT) with a maximum of 12 items and a short-form paper PTSD were developed based on Item Response Theory (IRT) modeling.

A related study based on this project examined the association of diagnostic criterion A2, the subjective emotional response to a potentially traumatic event (PTE) with PTSD diagnosis and symptom severity. We found that criterion A2 was not significantly associated with PTSD diagnosis. However, A2 endorsers reported greater PTSD symptom severity in all 3 PTSD symptom clusters (re-experiencing, avoidance, and hyperarousal) than those who did not endorse criterion A2, even after controlling for intensity of traumatic exposure.

In Phase 2 of the study the P-CAT and short form were validated against the three established measures of PTSD and a PTSD diagnosis based on a standardized interview (the PTSD module of the Standardized Clinical Interview for Diagnosis [SCID]). Findings suggested that a 12-item PCAT showed excellent discriminant validity, successfully discriminating veterans with PTSD from those with other mental health conditions and from those with medical, but no mental health conditions. Concurrent validity was also supported by high correlations with established PTSD self-report measures.

IMPACT:
Development of a the P-CAT has the potential to facilitate and enhance the VA's capacity for: 1) efficient, reliable and valid monitoring of the course of PTSD and the outcomes of its treatment; 2) assessing the severity of PTSD symptoms in veterans 3) efficiently and accurately identifing veterans suffering from PTSD and 4) expediting the processes for referral and entry into appropriate, evidence-based treatment programs. Computer-adapted health assessments will be transferable to existing VA clinical care systems such as the computerized patient record system, as well as new informatics initiatives such as MyHealtheVet. We are currently seeking additional funding to develop computer-generated reports to display results of the PCAT, as well as possible implementation opportunities.

PUBLICATIONS:

Journal Articles

  1. Osei-Bonsu PE, Spiro A, Schultz MR, Ryabchenko KA, Smith E, Herz L, Eisen SV. Is DSM-IV criterion A2 associated with PTSD diagnosis and symptom severity? Journal of traumatic stress. 2012 Aug 1; 25(4):368-75.
  2. Del Vecchio N, Elwy AR, Smith E, Bottonari KA, Eisen SV. Enhancing self-report assessment of PTSD: development of an item bank. Journal of traumatic stress. 2011 Apr 1; 24(2):191-9.


DRA: Mental, Cognitive and Behavioral Disorders
DRE: Diagnosis
Keywords: Clinical Diagnosis and Screening, PTSD
MeSH Terms: none

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