Exposure to critical incidents at work and development of posttraumatic stress among police officers: a 2-year prospective cohort study

Although post-traumatic stress disorder (PTSD) is a well-known risk for police officers, the understanding of underlying mechanisms is incomplete. This study aims to evaluate the cumulative burden model of PTSD development in 2,823 police officers. Using questionnaires, initially distributed in March 2021, with subsequent collections in 2022 and 2023 and shorter quarterly assessments, the association between the frequency of critical incident exposure and the development of PTSD symptoms is investigated. Additionally, the association between different levels of exposure within a year and the severity of PTSD symptoms is assessed as well as the risk of new incidents reaching threshold levels for PTSD based on the guidelines of the International Trauma Questionnaire. At the 24-month follow-up, 4.9% of the police officers had developed critical PTSD symptoms. The results reveal an exposure-response association between critical incidents and the development of PTSD with the risk of PTSD increasing in more exposed groups of officers. The cumulative burden model was supported but also nuanced, and prevention of PTSD development in police work and similar emergency occupations should focus on the strain of repeated exposure to critical incidents at work and not only reactions following single catastrophic incidents.