Violent victimisation in post-traumatic stress disorder: a Swedish register-based cohort study

Background: Post-traumatic stress disorder (PTSD) is associated with various adverse outcomes, but links with subsequent violent victimisation are uncertain. Methods: We linked data from Swedish sociodemographic and medical registers to create a matched cohort of people with diagnosed PTSD and a comparison sample matched on birth year, sex, and county of residence in the year preceding diagnosis (or matching in the case of undiagnosed individuals). We calculated the cumulative incidence of violent victimisation (defined using ICD codes registered at hospitalisation) and conducted stratified Cox regression analyses, adjusted for parental factors, psychiatric comorbidities, and history of violent victimisation. Findings: The cohort contained 29,688 individuals diagnosed with PTSD, who were matched with 296,880 individuals without PTSD (78.6% female), and followed for up to 34 years. Individuals with PTSD had higher cumulative incidences of violent victimisation after their index diagnosis (18.7% compared to 2.7% at 25 years follow-up). Individuals with both a diagnosis of PTSD and history of violent victimisation had the highest cumulative incidence (28.7%). After adjustment for parental characteristics, prior psychiatric comorbidity and prior violent victimisation, PTSD was associated with an adjusted hazard ratio of 4.0 (95% CI 3.7-4.4). Interpretation: Preventing subsequent violent victimisation among individuals diagnosed with PTSD should be considered by clinical services and incorporated into violence prevention strategies. Funding: AP is funded by the Wellcome Trust (grant code 218497/Z/19/Z). SF and AS are supported by the NIHR Oxford Health Biomedical Research Centre (grant BRC-1215-20005). No funder(s) listed had any role in the design or implementation of this study.