Researchers from the National Center for PTSD at the Boston V.A. conducted a long-term follow-up on participants 5-10 years after completing a randomized controlled trial comparing cognitive processing therapy (CPT) with prolonged exposure (PE) for posttraumatic stress (PTSD) on traumatized survivors of rape.
Intention-to-treat (ITT) participants were assessed 5-10 years after participating in the study (M = 6.15, SD = 1.22).  The investigators attempted to locate the 171 original participants - women with PTS who had experienced at least one rape.
Of the 144 participants located, 87.5% were reassessed (N = 126), which constituted 73.7% of the original ITT sample.  Self-reported PTS symptoms were the primary outcome.  Clinician-rated PTSD symptoms, comorbid diagnoses, and self-reported depression constituted secondary outcomes.

Findings indicated that substantial decreases in symptoms were maintained throughout the follow-up period (as reported in Resick, Nishith, Weaver, Astin, & Feuer, 2002). There was little change over time, with effect sizes ranging from pr = .03 to .14).  No significant differences emerged between the two treatment conditions (Cohen's d = 0.06-0.29).
The ITT examination of diagnostics indicated that 22.2% of CPT and 17.5% of PE participants met the diagnosis for PTSD according to the Clinician-Administered PTSD Scale (Blake et al., 1995). Maintenance of improvements could not be attributed to further therapy or medications.

The investigators concluded that both Cognitive Processing Therapy and Prolonged Exposure Therapy resulted in lasting changes in PTSD and related symptoms over an extended period of time for female rape victims with extensive histories of trauma.

Citation:  Resick PA, Williams LF, Suvak MK, Monson CM, Gradus JL. Long-term outcomes of cognitive-behavioral treatments for posttraumatic stress disorder among female rape survivors. Journal of Consulting and Clinical Psychology. 2012 Apr;80(2):201-10. Epub 2011 Dec 19. [email protected]