A randomized clinical trial comparing Interpersonal Psychotherapy with Prolonged Exposure for the treatment of PTSD in veterans

Trauma-focused therapies are recommended as first-line treatments for posttraumatic stress disorder (PTSD), but many veterans do not complete or sufficiently respond to these treatments. Interpersonal Therapy (IPT) is a non-trauma focused approach that directly addresses the interpersonal and social impairments associated with PTSD. This two-site randomized controlled equivalence trial compared IPT with Prolonged Exposure (PE) in improving PTSD symptoms and interpersonal functioning in 109 veterans with PTSD. Secondary outcomes included functioning and quality of life. We hypothesized that IPT would be statistically equivalent to PE in reducing PTSD symptoms, and superior to PE in improving interpersonal functioning and secondary outcomes of work and social adjustment and quality of life. PTSD symptom severity decreased significantly in both treatments from pre- to post-treatment. Although IPT improved as much as PE and treatments did not differ significantly, the 95 % confidence interval for the difference between the groups did not fall completely within the margin of equivalence. IPT was not superior to PE in improvement in interpersonal functioning or on secondary outcomes. Findings from multi-level linear mixed models using longitudinal data (posttreatment, three and six month follow up) for the primary outcomes of PTSD and interpersonal functioning were consistent with the post-treatment analyses. Although statistically inconclusive in terms of equivalence, the comparable reduction in PTSD symptoms slightly favoring IPT suggests that IPT is an acceptable alternative to gold-standard trauma-focused treatments for veterans with PTSD.