Overcoming Adversity and Stress Injury Support (OASIS): Evaluation of Residential Treatment Outcomes for U.S. Service Members with Posttraumatic Stress Disorder.

Research on residential posttraumatic stress disorder (PTSD) treatment has predominantly focused on the U.S. veteran population, whereas limited research exists regarding active duty service members. The present study evaluated outcomes among service members who received treatment in the Department of Defense's only residential PTSD program, Overcoming Adversity and Stress Injury Support (OASIS). Over a 5-year period, 289 male service members with combat-related PTSD received treatment in the program. Service members completed an initial assessment and weekly PTSD and depression self-report measures during the 10-week program. Multilevel modeling results demonstrated statistically significant reductions in PTSD. On average, participants reported a 0.76-point reduction on the PTSD Checklist, B = -0.76, p < .001, for each additional week of treatment. Pretreatment symptom scores and fitness-for-duty status predicted PTSD symptoms across time. Weekly changes in depression symptoms were not statistically significant; however, a significant Time × Pretreatment Depression Severity interaction emerged. Service members with higher baseline levels of depression severity showed larger reductions in depression symptom severity than those with lower levels, B = -0.02, p = .020, although a sizeable minority continued to retain symptoms at diagnostic levels. Depression symptom change was not related to any other treatment- or service-related variables. Differing trajectories were found between service members whose symptoms improved over the course of residential treatment and those who did not. The results indicate that there were larger improvements in PTSD than depression symptoms and highlight the need to optimize care provision for service members with severe PTSD or comorbid symptoms.