CSP #591 - CERV-PTSD: Comparative Effectiveness Research in Veterans With PTSD

VA Cooperative Study CSP #591 is designed to compare the effectiveness of Prolonged Exposure (PE) and Cognitive Processing Therapy (CPT) for treating posttraumatic stress disorder (PTSD) in male and female Veterans. PTSD is a serious and prevalent condition in Veterans, affecting just under 9% of VA patients in Fiscal Year 2011 (FY11). Since 2005, the number of VA patients with PTSD has increased 14.8% annually, due not only to new Veterans but also to increased numbers of Vietnam Veterans who are seeking care. In FY11, PTSD was the 3rd most common service-connected disability in VA.

Despite solid evidence that Prolonged Exposure and Cognitive Processing Therapy are effective treatments for PTSD in Veterans and non-Veterans, there is insufficient evidence about the effectiveness of these treatments relative to one another. The only study to compare the treatments, a single-site trial in non-Veteran female rape survivors, failed to find a difference, but the study was not adequately powered to compare two such effective treatments. Other data are similarly inconclusive. CSP #591 would break new ground as the first large-scale comparative effectiveness trial of treatment for PTSD and the first study to provide definitive information about how effective treatments for PTSD compare with one another.

The study will be a prospective randomized clinical trial with blinded assessment. The population will be male and female Veterans with PTSD due to any traumatic military event. Patients who are eligible and agree to participate in the study will be randomly assigned in a 1:1 ratio to receive Prolonged Exposure or Cognitive Processing Therapy. The investigators propose to administer 12 weekly sessions of each treatment as a standard "dose" but to allow participants who improve more rapidly to finish in 10 or 11 sessions and participants who have not attained adequate improvement by session 12 to have up to 2 additional sessions.

The primary outcome is improvement in PTSD symptom severity as measured by change on the Clinician-Administered PTSD Scale after treatment. The outcome measure will be determined from regular follow-up visits of the patients, which will occur at the middle and at the end of treatment and then 3 and 6 months later. Secondary outcomes include other measures of PTSD, comorbid mental health problems, functioning, quality of life, and service utilization. The investigators also will measure participants' treatment preference and examine whether concordance between preference and allocation is associated with increased treatment effectiveness.

In order to detect a standardized mean difference in improvement in PTSD symptom severity of d = .25, a sample size of 900 randomized patients provides 90% power to detect a difference between arms using the linear mixed effects model with a two-sided = .05. Given the lack of conclusive findings to predict which treatment is better, the investigators propose to test a nondirectional hypothesis. Assuming 2.5 years of accrual and an enrollment of 26 participants per year at each site, the investigators would need 14.1 sites to enroll a total of 64 participants per site. The investigators propose to recruit 17 sites to guard against the possibility that some sites will not enroll the required number of participants.