IntroductionWe studied whether provisional posttraumatic stress disorder (PTSD) moderated discharge (DC) and 6-month follow-up (FU) outcomes of multi-modal, integrated eating disorder (ED) residential treatment (RT) based upon principles of cognitive processing therapy (CPT).MethodsED patients [N = 609; 96% female; mean age (± SD) = 26.0 ± 8.8 years; 22% LGBTQ +] with and without PTSD completed validated assessments at admission (ADM), DC and 6-month FU to measure severity of ED, PTSD, major depressive disorder (MDD), state-trait anxiety (STA) symptoms, and eating disorder quality of life (EDQOL). We tested whether PTSD moderated the course of symptom change using mixed models analyses and if ED diagnosis, ADM BMI, age of ED onset and LGBTQ + orientation were significant covariates of change. Number of days between ADM and FU was used as a weighting measure.ResultsDespite sustained improvements with RT in the total group, the PTSD group had significantly higher scores on all measures at all time points (p ≤ .001). Patients with (n = 261) and without PTSD (n = 348) showed similar symptom improvements from ADM to DC and outcomes remained statistically improved at 6-month FU compared to ADM. The only significant worsening observed between DC and FU was with MDD symptoms, yet all measures remained significantly lower than ADM at FU (p ≤ .001). There were no significant PTSD by time interactions for any of the measures. Age of ED onset was a significant covariate in the EDI-2, PHQ-9, STAI-T, and EDQOL models such that an earlier age of ED onset was associated with a worse outcome. ADM BMI was also a significant covariate in the EDE-Q, EDI-2, and EDQOL models, such that higher ADM BMI was associated with a worse ED and quality of life outcome.ConclusionsIntegrated treatment approaches that address PTSD comorbidity can be successfully delivered in RT and are associated with sustained improvements at FU. Improving strategies to prevent post-DC recurrence of MDD symptoms is an important and challenging area of future work.