Treatment Efficacy for Veterans With Posttraumatic Stress Disorder: Latent Class Trajectories of Treatment Response and Their Predictors.

Evidence suggests that veterans with posttraumatic stress disorder (PTSD) have a poorer treatment response than nonveterans.  In this study, we explored heterogeneity in treatment response for 960 veterans in the United Kingdom with PTSD who had been offered a residential intervention consisting of a mixture of group sessions and individual trauma-focused cognitive behavioral therapy (TF-CBT). The primary outcome was PTSD score on the Impact of Event Scale-Revised (IES-R).  Covariates included depression, anxiety, anger, alcohol misuse, functional impairment, and sociodemographic characteristics.  Follow-up occurred posttreatment at set time points for 12 months.  We present predictors of PTSD severity at posttreatment and follow-up obtained using a latent class growth analysis to identify different treatment trajectories.  Multinomial logistic regression models were used to identify covariates predicting class membership, and five classes were identified. Of participants, 71.3% belonged to three classes showing positive treatment responses, and 1.2% showed initial improvement but later relapsed. Additionally, 27.5% of participants were identified within a treatment-resistant class that showed little change in severity of presentation. Depression, anxiety, and having had a combat role during military service increased the likelihood of membership in the treatment-resistant class, odds ratios (ORs) = 1.12-1.53, 1.16-1.32, and 2.89, respectively. Additionally, participants in the treatment-resistant class had higher pretreatment PTSD scores for reexperiencing, avoidance, and hyperarousal symptoms, ORs = 5.24, 2.62, and 3.86, respectively. Findings suggest the importance of triaging individuals and offering interventions tailored to severity of presentation.