{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T17:02:22Z","timestamp":1785862942728,"version":"3.56.0"},"reference-count":60,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T00:00:00Z","timestamp":1781827200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T00:00:00Z","timestamp":1781827200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Psychother Psychosom"],"abstract":"<jats:p>Introduction: Ketamine combined with psychotherapy has shown promise in treating posttraumatic stress disorder (PTSD), but predictors of clinical benefit remain unclear. In this systematic review and individual participant data meta-analysis (IPDMA), we examined patient- and treatment-level predictors of PTSD symptom change after combined treatment. Methods: Eligible studies combined ketamine with psychotherapy in adults with PTSD. The primary outcome was PTSD symptom change on the PTSD Checklist for DSM-5 (PCL-5). We fit linear mixed-effects models with a random intercept for study and fixed effects for age, sex, baseline PCL-5, number of ketamine sessions, number of psychotherapy sessions, administration route, and treatment duration. Sex-stratified analyses and a quality-restricted sensitivity analysis were conducted. Results: Twelve studies (533 participants) were included; nine were of poor quality. Greater improvement was associated with more psychotherapy (\u03b2 = 1.03 per session) and more ketamine sessions (\u03b2 = 1.15 per session), higher baseline symptom severity (\u03b2 = 0.50 per PCL-5 point), and shorter treatment duration (\u03b2 = \u22120.58 per week). Between-study heterogeneity was nontrivial (intraclass correlation coefficient \u2248 0.15). In sex-stratified models, number of psychotherapy sessions, baseline severity, and shorter treatment duration remained associated with improvement in both sexes. In the sensitivity analysis (n = 63), baseline severity was the only significant predictor of treatment outcome. Conclusion: Higher baseline PTSD severity was the most robust predictor of symptom reduction. Session intensity and treatment timing may matter, but associations should be interpreted cautiously given the predominance of poor-quality studies and require replication in prospective trials with standardized protocols and longer follow-up.<\/jats:p>","DOI":"10.1159\/000553144","type":"journal-article","created":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T16:01:06Z","timestamp":1781884866000},"page":"1-13","source":"Crossref","is-referenced-by-count":0,"title":["Ketamine-Assisted Psychotherapy for Posttraumatic Stress Disorder: A Systematic Review and Individual Participant Data Meta-Analysis of Predictors of Treatment Effects"],"prefix":"10.1159","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7424-058X","authenticated-orcid":false,"given":"Judith","family":"Rohde","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tyler 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