Long-term effectiveness of a prolonged exposure-based intensive outpatient program for veterans with posttraumatic stress disorder.

Empirically-supported psychotherapies for posttraumatic stress disorder (PTSD) are highly effective and recommended as first-line treatments, yet dropout rates from standard outpatient therapy are high. Intensive outpatient programs (IOPs) that provide these therapies in condensed format with complementary interventions show promise, as they have demonstrated similar efficacy and higher retention rates. The current study examined initial and long-term outcomes up to 12-months following a 2-week PTSD IOP involving daily prolonged exposure therapy (PE) and adjunctive interventions for veterans and military service members. Participants (N = 376) demonstrated high retention (91%) and large effect size reductions in self-reported PTSD and depression symptoms after two weeks. Small increases in symptoms occurred after 3 months but these stabilized and large reductions compared to baseline were maintained up to 12 months. Piecewise multilevel modeling indicated that demographic variables did not predict PTSD or depression symptom trajectories. Higher PTSD and depression severity at intake predicted higher symptomatology across timepoints and larger relative gains during treatment. Greater alcohol use prior to treatment was associated with higher PTSD symptomatology but did not affect the magnitude of gains. A history of childhood sexual abuse was associated with greater reduction in depression symptoms over treatment, although this effect faded over follow-up. Together these findings underscore the long-term effectiveness of a PE-based IOP across a diverse range of veterans and service members.