- Impact of Killing psychotherapy produced significantly greater improvement on Sheehan Disability Scale and reduced PTSD and moral injury symptoms compared with present-centred therapy.
- Both IOK and present-centred therapy improved psychosocial functioning on WHOQOL-BREF and SDS at posttreatment.
- Multisite randomised clinical trial of 100 veterans with PTSD related to killing; blinded assessments at baseline, posttreatment, and six-month follow-up.
JAMA Psychiatry. 2026 Aug 5. doi: 10.1001/jamapsychiatry.2026.2307. Online ahead of print.
ABSTRACT
IMPORTANCE: Killing in war is associated with multiple adverse outcomes, including posttraumatic stress disorder (PTSD), moral injury (MI), and suicide. Impact of killing (IOK) is an individual psychotherapy developed to treat the mental health impact of killing in war.
OBJECTIVE: To determine whether IOK improves veterans’ mental health symptoms and functioning at posttreatment and 6-month follow-up.
DESIGN, SETTING, AND PARTICIPANTS: This multisite, superiority, randomized clinical trial was conducted from August 2018 to November 2023. Participants were veterans randomized to IOK or present-centered therapy (PCT). Diagnostic assessments were administered at screening and posttreatment by blinded evaluators. Self-report measures were collected at baseline, midtreatment, posttreatment, and 6-month follow-up at 3 Veterans Affairs health care systems in California, New York, and North Carolina via in-person and remote appointments. Participants were a sample of veterans with PTSD who reported distress related to killing in war or feeling responsible for the death of others. Primary exclusion criteria were a psychotic disorder diagnosis, moderate or severe alcohol or substance use disorder, untreated mania, or recent suicidal or homicidal behavior.
INTERVENTIONS: IOK, an individual psychotherapy that focuses on killing cognitions, acceptance, self-forgiveness, and moral repair, and PCT, which addresses current functional issues due to moral distress with related problem-solving.
MAIN OUTCOMES AND MEASURES: The primary outcomes were psychosocial functioning assessed by the World Health Organization Quality of Life Scale-Brief (WHOQOL-BREF) and the Sheehan Disability Scale (SDS). Secondary outcomes included PTSD and MI measures.
RESULTS: A total of 100 individuals (98 male; mean [SD] age, 48.4 [13.7] years) were randomized. Linear mixed models revealed that psychosocial functioning improved for both groups at posttreatment (WHOQOL-BREF and SDS) and the IOK group had a significantly greater improvement than those in PCT on the SDS (-3.50; z score, -2.42; Cohen d, -0.51; P = .02; 95% CI, -5.65 to -0.59). There was no significant difference between treatments on the WHOQOL-BREF at posttreatment. Compared to PCT participants, IOK participants also reported significantly greater improvement in PTSD and MI symptoms.
CONCLUSIONS AND RELEVANCE: Individuals in both treatments improved on measures of psychosocial functioning (WHOQOL-BREF and SDS). Those who received IOK evidenced greater improvements in work or school, social life, and home or family life (as measured by the SDS) compared to those in PCT at posttreatment. IOK participants also reported improved PTSD and MI symptoms. The findings suggest that IOK may improve several outcomes for those who experience distress due to killing in war.
TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03764033.
PMID:42555019 | DOI:10.1001/jamapsychiatry.2026.2307
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