Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT00651872 |
| Other study ID # |
PT074941 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
N/A
|
| First received |
April 1, 2008 |
| Last updated |
March 5, 2014 |
| Start date |
June 2008 |
| Est. completion date |
June 2013 |
Study information
| Verified date |
August 2013 |
| Source |
Boston VA Research Institute, Inc. |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
United States: Institutional Review Board |
| Study type |
Observational
|
Clinical Trial Summary
This project has the long-term goal of designing and validating a psychometrically sound
inventory of PTSD-related functional impairment for active duty service members and
veterans. The inventory will include assessments of multiple dimensions of functional
impairment and their impact on quality of life and explicitly show how PTSD symptoms are
related to functional impairment. By creating and validating an inventory to assess
PTSD-related functioning--as they are perceived and reported by active military personnel
and veterans--we hope to offer a useful tool for clinicians, researchers and military
leaders. A measure of PTSD-related functional impairment will have enormous value from a
health care perspective in terms of identifying individuals with the disorder and for
promoting more efficient allocation of resources and efforts towards those who are in most
need. We anticipate that the end product of this study, an efficient, empirically-based
measure of PTSD-related functional impairment will have an immediate impact on the
assessment and treatment of military-related PTSD, in terms of promoting more efficient
allocation of resources and efforts towards those who are in most need. Such a measure will
also assist with PTSD-related compensation and pension procedures and decisions by providing
a means to more accurately assess PTSD-related functional impairment.
Description:
In the first phase of this project, we will convene a series of focus groups, whose members
will be a convenience sample (n = 53) selected from veterans at the Boston VAMC. These
groups will be used to set forth formal definitions of the PTSD-related functional
impairment variables, create an item pool, and refine that pool with emphasis on standards
of content validity, both content relevance and content breadth.
Using what in psychometrics is called the rational method to instrument construction
(Edwards, 1970; Hulin, Drasgow, & Parsons, 1983; Nunnally, 1978), the first step will be to
carefully delineate complete and clearly expressed written definitions of the PTSD-related
dimensions of functioning and quality of life. Another important source of information will
be veterans of various conflicts with military-related PTSD in four focus group sessions.
The intent will be to pose a series of structured questions aimed at eliciting group
members' functional impairments and quality of life issues related to their PTSD. Next, a
table of specifications (Aiken, 1994) will be employed to aid in the orderly construction of
items across content areas. In this regard, for each of the functional impairment
dimensions, separate aspects of the definition will be identified, and items will be written
so as to systematically represent these aspects.
The end result of these steps should be an initial pool of 30 to 35 items for each
construct. Consistent with classic psychometric guidelines (e.g., Nunnally, 1978), this
number of items should be adequate to produce individual scales with 15 to 20 items each,
which, in turn (if the rational approach described above has been faithfully followed),
should be a sufficient number to exhibit acceptable psychometric characteristics.
Phase 2 has the objective of selecting the best final sets of items to measure the
identified dimensions of PTSD-related functional impairment as well as to assess
criterion-related validity. Using empirically derived item and scale characteristics, we
will trim the item pool to arrive at smaller, higher-quality, and more parsimonious sets.
For all scales, content relevance and content breadth, in line with the formal definition of
each factor, will be maintained.
Data collection and additional instrumentation. The test development sample will be selected
in accordance with the sampling plan. Two hundred and eighty six consenting veterans at the
Boston VAMC will participate in interviews, each lasting approximately two hours.
Eighty-five percent of participants will be male and 15% will be female. We aim to collect
data from veterans who meet criteria for current PTSD (one-third of sample) as well as those
who meet criteria for lifetime but not current PTSD (one-third of sample) and those who have
been traumatized but do not meet criteria for current or lifetime PTSD (no PTSD; one-third
of sample). Further, we will collect data on a diverse sample of veterans, with
representation from Vietnam, Persian Gulf, and OEF/OIF conflicts.
Historical/demographic information will be obtained during the interview as well as through
chart review concerning the following variables: age, race, socioeconomic status, current
annual income, employment, education, and marital status. In addition, historical data
regarding illegal behaviors, suicide attempts, psychiatric hospitalizations, prescription
medications, interpersonal conflicts, and service connection disability status will be
collected. We will also obtain pertinent information from veterans' DD-214, including
declaration of combat theatre duty, military occupational specialty, and combat medals
awarded.
PTSD diagnosis will be assessed using the Clinician-Administered PTSD Scale for DSM-IV
(CAPS). The CAPS was designed to improve the reliability and validity of PTSD assessment.
Since its development, the CAPS has become the gold standard for arriving at a PTSD
diagnosis, either current or lifetime, and has been used in more than 200 published studies.
Functional impairment will be assessed using several established measures. The Medical
Outcomes Study 36-item Short Form Health Survey-veterans version (SF-36V; Ware & Sherbourne,
1992) provides eight domain scores indexing physical functioning, physical role, bodily
pain, general health, vitality, social functioning, emotional role, and mental health; in
addition, summary physical and mental health scores may be computed. The reliability and
validity of the SF-36 are well documented (e.g., McHorney, Ware, & Raczek, 1993).
The World Health Organization Disability Assessment Schedule II (WHODAS II) is a measure of
functional disability which assesses a wide-range of impairment and disability dimensions
using multi-item scales including pain, concentration, understanding and communicating,
mobility, self care, family burden, getting along with others, household and work activities
and work loss, and participation in society (Appendix A:WHODAS). The WHODAS-II is becoming
widely used in investigations of functional disability across wide-ranging populations,
including the physically ill (i.e. rheumatology, pulmonary, primary care cohorts) and
severely mentally ill (schizophrenic cohorts). Although patients with PTSD and related
anxiety disorders were included in the original multi-center development of the instrument,
the WHODAS-II has not been employed specifically with trauma survivors. For this study, we
will use the 36-item self-report version of this scale. Scores for each of the 6 individual
domains, as well as an overall score of global functional disability can be calculated.
The Global Assessment of Functioning (GAF) is the standard method for representing a
clinician's judgment of a patient's overall level of psychosocial functioning. As such, it
is probably the single most widely used method for assessing impairment among patients with
psychiatric or substance use disorders or both. The GAF requires a clinician to make an
overall judgment about a patient's current psychological, social, and occupational
functioning. In DSM-IV-TR, this rating is made on a scale from 1 to 100, with ratings of 1
to 10 indicating severe impairment and ratings of 91 to 100 indicating superior functioning.
GAF ratings of impairment are modestly associated with some indexes of social functioning,
such as the extent of social networks and the need for support, and with residential
instability, lack of employment, and poor work adjustment. In general, however, these
relationships are relatively weak; GAF ratings tend to be more closely associated with
diagnoses and psychiatric symptoms than with social and occupational functioning.
General life satisfaction, defined as "an individual's evaluation of the degree to which his
or her most important needs, goals, and wishes have been fulfilled" (Frisch, Cornell,
Villanueva, & Retzlaff, 1992, p. 93) will be measured using the Quality of Life Inventory
(Frisch, 1992), a 16-item instrument employing a Likert-type response format and producing a
weighted summative score across multiple facets of life satisfaction (e.g., standard of
living, work, home, and relationships with relatives). The psychometric qualities for this
measure are strong, with high test-retest and internal consistency reliability and strong
validity coefficients for clinical and community samples, including veterans.
To assess malingering, participants will be completing the M-FAST (Miller, 1995). The M-FAST
is a brief 25-item screening interview for individuals ages 18 years and older that provides
preliminary information regarding the probability that he/she is feigning psychiatric
illness. Most malingering and symptom validity instruments assess malingered cognitive
and/or neuropsychological deficits. The M-FAST focuses exclusively on malingered psychiatric
illness including Depression, Schizophrenia, Hypervigilance, Personality Disorder,
Nightmares, and a Suggestibility Interview.
Analytic procedures and interpretation. Classical test theory-oriented item characteristics
will be computed (Aiken, 1994; Anastasi, 1982; Nunnally, 1978). For the items that are
accompanied by multipoint Likert-type response formats ("strongly disagree" to "strongly
agree"), frequency distributions and descriptive statistics first will be calculated. Items
having a symmetric response distribution will be preferred over items having a skewed
distribution. Finally, corrected item-total correlations, the correlations of each item's
score with the sum of scores on all other items measuring that construct, will be computed,
where appropriate to the construct. Item-total correlations are indices of an item's ability
to distinguish among those high and low on the attribute and thus are indicative of the
item's precision of measurement. Items with higher item-total correlations typically take
precedence over those with lower item-total correlations. Using judgments of content
validity, distributional and endorsement patterns and statistics, and item-total
correlations, a final set of items for each construct will be chosen. Estimates of internal
consistency reliability (Cronbach's alpha) will then be calculated. At the close of Phase 2,
the product will be a refined inventory of PTSD-related functional impairment.
Phase 3 involves the collection of data from a second-stage test sample to support cross
validation and criterion-related validity. Refined measures of the previously identified
dimensions of PTSD-related functional impairment, along with measures of PTSD and other
health outcomes will be administered to an active duty sample and another veteran sample.
Data collection and additional instrumentation. Seventy-five percent of participants will be
male and 25% will be female. Participants will be administered the refined and shortened
version of the inventory as well as scales intended to assess physical and mental health,
health-related quality of life, functional impairment, and social desirability. Data
collection is expected to last 60-75 minutes for each participant.
With the exception of the CAPS and MFAST, all of the measures used in Phase 2 will be
employed in Phase 3. In place of the CAPS, we will use the PTSD Checklist (PCL; Weathers et
al., 1993) to assess PTSD symptoms. The PCL has good sensitivity and specificity and is
positively correlated with standard measures of PTSD. In place of the MFAST, we will the
SIMS.
Analytic procedures and interpretation. Data from this test validation phase will offer a
second opportunity to compute internal consistency reliability (Cronbach's alpha) for the
measures of functional impairment. It is important to re-estimate and reexamine internal
consistency on a fresh sample since the estimates derived on the same sample from which the
items were selected (Phase 2) take advantage of sample-specific covariation and may be
somewhat inflated. It is also critical to cross-validate the initial findings with an
independent sample in order to ensure that the items which comprise the developed functional
impairment scale are optimal.
