The role of dosage and intensity in trauma-focused treatments for posttraumatic stress disorder: A meta-analysis

Trauma-focused psychological interventions are widely recognized as the most efficacious treatments for posttraumatic stress disorder (PTSD); however, high rates of non-response and treatment discontinuation remain significant challenges. Modifying treatment dosage and intensity has been proposed as a promising strategy to enhance both efficacy and acceptability. This meta-analysis aimed to investigate whether factors related to treatment dosage and intensity moderate effects on PTSD and depression symptom severity, as well as treatment completion rates, in guideline-recommended PTSD treatments (PROSPERO: CRD42023485646). A systematic literature search was conducted in the PTSD Trials Standardized Data Repository, databases, and previous meta-analyses. Eligible trials were randomized controlled trials (RCTs) evaluating trauma-focused interventions delivered individually and in person to adults diagnosed with PTSD. Studies published until October 6, 2025, were considered for inclusion. Study quality was assessed using Cochrane's RoB 2 tool. Moderator analyses were conducted through meta-analyses of head-to-head trials comparing arms with deliberate variations in dosage or intensity, and meta-regression analyses. A total of 73 RCTs, comprising 5696 participants, were included. Interventions showed medium to large overall effects on PTSD and depression, with an average completion rate of 71.8%, 95% CI [68.3%, 75.0%]. Moderator analyses indicated weaker between-group effect sizes for PTSD with a greater number of trauma-focused sessions, stronger effect sizes with a higher number of completed sessions and personalized session numbers, and higher completion rates for highly intensive treatments. These findings suggest that PTSD treatment outcomes may be influenced by dosage and intensity, with personalizing session numbers and increasing treatment intensity appearing particularly beneficial.