PTSD and Complex PTSD in Residential Treatment for Eating Disorders: Moderating Effects on Symptom Severity and Outcome Trajectory

Objective: Eating disorders (EDs) and symptoms of trauma commonly co-occur, yet research is limited on how trauma affects ED treatment outcomes. This is particularly true for complex post-traumatic stress disorder (CPTSD). Differentiating between the treatment impacts of PTSD and CPTSD (which includes both PTSD symptoms and disturbances in self-organization [DSO]) may help ED providers address this common comorbidity. Method: The current study included 95 women (M_age = 26 years) with EDs (largely anorexia nervosa) who received residential treatment (M = 81 days). Participants completed measures of ED symptoms, anxiety, depression, body mass index (BMI), ED-specific health-related quality-of-life (ED-HRQoL) impairment, functional disability, and trauma symptoms at admission, week 4 of treatment, discharge, and 6 months post-discharge. Results: All outcomes except BMI were more severe at admission and week 4 of treatment for individuals with comorbid trauma (based on probable CPTSD or exceeding the clinical threshold for PTSD and DSO symptom domains); however, these differences resolved by discharge and remained non-significant at follow-up. Some forms of comorbid trauma moderated outcome trajectories for anxiety, depression, and disability (but not ED symptoms), such that individuals with comorbid trauma showed slower improvement early in treatment, steeper improvement later in treatment, and greater resurgence after discharge. Discussion: These findings highlight that PTSD and CPTSD symptom domains may be associated with more severe ED outcomes early in residential treatment that resolve by discharge, and may predict differential treatment response for secondary outcomes. Implications are discussed for clinical assessment and treatment of comorbid trauma-related disorders in residential care. Trial Registration: The study was prospectively registered on the Australian and New Zealand Clinical Trials Registry in November 2021, registration number ACTRN12621001651875.