Improving Voluntary Engagement for PTSD Treatment Among Service Members
Phase: NA
Conditions: Posttraumatic Stress Disorder
Sponsor: University of Washington

 
 
 
 
 
 
 
 
 
 
Official Title of the Study: 
Improving Voluntary Engagement for PTSD Treatment among Service Members 
 
 
 
Date: 
January 30, 2018 
 
 
 
NCT ID: 
Not yet assigned 
 
 

STUDY PROTOCOL 
 
Objectives 
This study will develop and test a brief motivational enhancement intervention for active duty 
Army and Air Force personnel who are experiencing symptoms of PTSD and who are not 
currently in treatment. The intervention is designed to prompt: (1) a willingness to participate 
voluntarily in a self-appraisal of PTSD symptoms, (2) increased perceptions of PTSD treatment 
effectiveness, (3) reduced perceptions of stigma associated with mental healthcare, (4) 
engagement in PTSD treatment or other self-help programs, and (5) reductions in PTSD 
symptoms. The proposed study will test the efficacy of this intervention against a comparison 
condition of treatment-as-usual – written referrals to treatment options. 
 
Hypotheses 
H1: Individuals receiving the MET intervention will report more PTSD treatment engagement at 
follow-up relative to participants in the comparison condition. 
H2: Individuals receiving the MET intervention will experience fewer PTSD symptoms at 
follow-up relative to participants in the comparison condition. 
H3: The effect of the intervention on PTSD symptoms will be mediated by PTSD treatment 
engagement. 
H4: The impact of the intervention on PTSD treatment engagement at the 6-month follow-up 
will be mediated by decreased perceived stigma associated with PTSD treatment and increased 
perceived effectiveness of treatment for PTSD, both of which will be targeted by the MET 
intervention. 
 
Methods 
Design. In a randomized controlled trial, the experimental (MET) and control (TAU) 
interventions will be compared. Participants (N = 200) will be randomly assigned to receive the 
MET condition or TAU. Both interventions will be preceded by telephone-administered 
screening and baseline assessments. Telephone administered follow-up assessments at 1 week, 3, 
and 6 months will assess post-intervention change in pertinent intentions, treatment participation, 
behaviors, symptoms, and perceptions of stigma and treatment effectiveness. 
 
Study Population. Study participants will be active duty Army and Air Force personnel 
stationed at Joint Base Lewis-McCord (JBLM). JBLM has a population of active duty personnel 
of approximately 46,496 (LTC Courtemanche, 2014). The demographic characteristics of the 
JBLM sample are expected to mirror demographic characteristics of Army and Air Force 
personnel in general. Participant selection will be equitable – inclusion/exclusion criteria are 
minimal and there are no limitations on age, race, ethnicity or sex included in the study. 
 
Eligibility Criteria. Eligibility for enrollment and random assignment to the two conditions will 
be based on the following criteria: 1) current PTSD, 2) not currently being treated (counseling 
and/or medication) for PTSD, and 3) currently serving in the Army or Air Force. Exclusion 
criteria include: 1) non-fluency in English, 2) evidence of psychosis, 3) pending deployment that 
would preclude completion of follow-ups. Callers who do not meet eligibility criteria, but who 
are concerned about PTSD symptoms, will be provided the opportunity to speak with a counselor 
and to discuss their thoughts and concerns surrounding their symptoms. Counselors will provide 

a 15-45 minute Motivational Interviewing (MI) session focused on their PTSD symptoms, and an 
exploration of options for ongoing support. Referrals to local treatment agencies and self-help 
options will also be available to the ineligible caller. 
 
Relevant Scientific Background 
Posttraumatic Stress (PTS) is associated with serious health and psychological effects. The 
health and well-being of military personnel, and consequently the capacity for optimal 
functioning of military units, are compromised by PTS. Rates of PTS are high among military 
personnel with post-deployment rates ranging from 5-20% (Hoge et al., 2004). Untreated PTS is 
associated with high rates of suicide, medical services utilization, relationship impairment, legal 
difficulties, decreased worker productivity, and decreased military readiness (Hoge et al., 2006; 
Hoge et al., 2007; Kline et al., 2010; Tanielian et al., 2008). 
 
Interventions can lead to long-lasting reductions in PTS symptom severity. There are multiple 
effective interventions for PTS with a high degree of research evidence supporting their efficacy 
(Bisson & Andrew, 2005; Bradley et al., 2005), including trauma-focused cognitive behavioral 
therapies (e.g., Prolonged Exposure, Cognitive Processing Therapy and Eye movement 
Desensitization and Reprocessing) and pharmacotherapies (e.g., SSRIs) (Forbes et al., 2010; 
VA/DoD, 2004). However, while treatment can be effective, individuals may not seek treatment. 
Drop-out and medication noncompliance are common. Despite treatment options, the majority of 
military personnel affected by PTS do not present for treatment (Steenkamp & Litz, 2013). For 
example, less than 10% received the recommended exposure to PTSD treatment by attending 9 
or more VA mental health treatment sessions in 15 weeks or less during the first year of PTSD 
diagnosis (Seal et al., 2010). For medications, on average, approximately 30% of those 
prescribed medications for PTSD also drop out (Ravindran & Stein, 2009). 
 
Military personnel encounter more real and perceived barriers to seeking treatment than people 
in the general community, such as stigma, fear of a diagnosis appearing on one’s service record, 
the perception that diagnosis would reflect negatively on one’s unit, work interference, 
geographical distance, and the belief that treatment is ineffective (Gould et al., 2007). 
 
A brief, telephone-delivered motivational enhancement intervention (MET) called a “check-up,” 
has shown promise in promoting self-initiated behavior change as well as voluntary treatment 
entry, enhanced retention, and more successful outcomes for soldiers with substance use 
disorders (Walker et al., 2017). Why MET for PTS? Efficacious options for treatment are 
available for PTS and the military has invested considerable resources into scaling up access to 
care. However, rates of self-referral and retention are low among active duty military. Given the 
availability of effective treatments contrasted with the low rates of military personnel who 
present and complete treatment, figuring out how to connect individuals with PTSD symptoms 
into treatment and then helping them to stay engaged is a high priority. Adapting the “check-up” 
for application with military personnel experiencing PTS symptoms is warranted for three key 
reasons: (1) it has the potential of overcoming barriers to treatment seeking, i.e., stigma and 
apprehension of a negative impact on one’s military career; (2) it has the potential of attracting 
voluntary participation; and (3) protocols for disseminating this low-cost intervention for use 
with deployed military can readily be developed and evaluated. 
 

Summary. Adapting the “check-up” variant of motivational enhancement therapy for 
application with military personnel is warranted for three key reasons: (1) permitting anonymous 
participation through a telephone delivered intervention has the potential of overcoming a major 
barrier to treatment-seeking among those who are concerned about their behavior, i.e., stigma 
and apprehension that being identified as having PTSD will negatively impact one’s military 
career and providing information about efficacy; (2) the nature of the check-up intervention as an 
opportunity to take stock of one’s PTSD experiences without being pressured to change, and the 
use of an empathic counseling style in its delivery, have the potential of attracting voluntary 
participation among individuals who would otherwise be deterred by concerns of being judged 
negatively and of being pressured to enter treatment; and (3) if the check-up is efficacious in 
voluntarily recruiting untreated service personnel with PTSD and promoting treatment 
engagement, support group participation, or self-initiated behavior change, protocols for 
disseminating this low cost and brief intervention for use with deployed military can readily be 
developed and evaluated. 
 
 
 

STATISTICAL ANALYSIS PLAN 
 
The primary data assessed at baseline and follow-up points via interviews and questionnaires 
will be entered into SPSS for Windows data entry (DE) files. Out-of-range values and skip rules 
will be built into DE files to facilitate data entry. All data will be double entered into the DE files 
by two different people to ensure accuracy. 
 
Following data cleaning, initial analyses will focus on assessing the psychometric properties of 
the assessments and constructing scale scores where appropriate. Univariate and bivariate 
descriptive analyses will be performed to examine distributions of and correlations among key 
study variables. In the event that variables show non-normal distributions (which could lead to 
violation of regression model assumptions), we will consider using generalized forms of models 
(e.g., Poisson or negative binomial count regression) or transformation of the outcome 
variable(s) of interest. 
 
Hypotheses 1 and 2 evaluate whether MET participants will report more treatment engagement 
and fewer PTSD symptoms at follow-up than TAU participants. This study will 4 have repeated 
measures from baseline to 6 months follow-up yielding up to 800 observations. Given the 
nesting of observations within individuals, we will run linear mixed (also known as hierarchical 
linear or multilevel) models (Diggle, Heagerty, Liang, & Zeger, 2002) to test study hypotheses. 
Measures of PTSD symptoms (CAPS) and treatment engagement (TAQ) will be analyzed as 
outcomes in separate models. Fixed effects will include indicator variables for time (1-week, 
3-months, 6-months) with baseline as the reference, intervention condition, and the interaction 
between time point and condition. The following represents the basic model: 
 
Level 1: Yti = π0 + π1(Time1wk)i + π2(Time3m)i + π3(Time6m)i 
Level 2: π0 = β00 + β01(Treat) + r00i 
π1 = β10 + β11(Treat) + r10i 
π2 = β20 + β21(Treat) + r20i 
π3 = β30 + β31(Treat) + r30i 
 
where Yti represents the continuous outcome for individual i at time t; Time1wk, Time3m, and 
Time6m are the indicator variables for study time points where baseline is the reference; Treat 
represents the variable for intervention condition; and r00i through r30i represent random subject 
specific deviations from the corresponding overall intercept or slope. Of particular interest are 
the coefficients β11, β21, and β31, which describe the cross-level interactions between 
intervention condition and time. For analyses of PTSD symptom score as the outcome, we expect 
that these interaction terms will be negative and statistically significant suggesting that PTSD 
symptoms are lower at follow-up visits among those randomized to the MET intervention 
compared to those in the control group. We will consider inclusion of additional covariates such 
as gender, social support, and trauma severity to improve precision of estimates. We will also 
explore modeling time as a continuous measure to assess treatment differences on slopes over 
time. Similar mixed effects models will be used to test effects of the intervention on 
stigma/barriers to treatment (PSBCPP) and treatment expectancies (CEQ) as well as secondary 
outcomes such as anxiety and depression symptoms. 
 

For analyses involving multiple outcomes, we will guard against Type I error by adjusting 
criteria for statistical significance for multiple testing (e.g., using global tests that test for an 
overall difference across outcomes while accounting for their inter-correlation or Benjamini- 
Hochberg corrections for the false discovery rate) where appropriate. 
 
For hypothesis 3, we will test whether the effect of the intervention on PTSD symptoms will be 
mediated by PTSD treatment engagement. For hypothesis 4, we will test whether effects of the 
intervention on treatment engagement are mediated through stigma and treatment expectancies. 
We will evaluate the effect of the intervention on change in the outcome (e.g., PTSD symptoms) 
both before and after controlling for the putative mediator(s) (e.g., treatment engagement) using 
the method described by Krull and MacKinnon (1999; 2001). Reduction in the percentage of 
variance accounted for by the interaction effect after controlling for the mediator(s) will inform 
the degree to which the effect is mediated. 
 
Missing Data and Attrition 
Based on retention rates in our ongoing clinical trial, we expect no more than 20% attrition by 6- 
month follow-up in this proposed study. Linear mixed models provide unbiased estimates in the 
presence of missing data as long as it can be considered ignorable (Atkins, 2005). Missing data 
are ignorable if they are either missing completely at random or related to variables in the 
analysis, including earlier time points of the outcome (Graham, 2009). Little efficiency is lost in 
linear mixed models with 10%-20% missing data. As a safe-guard against the possibility of 
nonignorable missing data, we will use pattern-mixture models for non-ignorable missing data 
that directly assess sensitivity of findings to the presence of missing data (Atkins, 2005). 
 
Sample Size and Power 
This study was powered to detect differences in PTSD symptoms between the intervention 
condition and control group over time. We used a simulation-based approach to estimate power 
for this study (Gelman & Hill, 2007). Using R statistical software, 1,000 datasets were generated 
based on the linear mixed model equation provided in the Analysis Plan. Estimates for model 
parameters for standardized PTSD scores (e.g., baseline intercept, slopes for time, distribution of 
random effects) were guided by preliminary data from our ongoing clinical trial. We also 
specified missingness of 13% and 19% at 3- and 6-month follow-up, respectively, according to 
missing data patterns in the ongoing trial. The model was fit for each of the 1000 datasets. A 
number of simulation runs were conducted varying the size of the treatment effects and fixing 
the sample size to 200. The percentage of datasets where the treatment-by-time interactions were 
statistically significant provides an estimate of power. Based on these simulations, this study 
should have >.8 power to detect effect sizes of .36 or greater at any given follow-up visit. An 
effect size of .36 is at the lower end of the range found in the extant literature on treatment for 
PTSD in military samples. The conservative estimate seems appropriate given the non-treatment 
seeking nature of the population yet is still clinically meaningful. For instance, a .35 effect size 
translates to a mean difference of approximately 6 points between conditions on the PTSD 
symptom checklist based on data collected in our current ongoing trial.