Trajectories of posttraumatic stress symptoms following collective violence: A systematic review and meta-analyses.

Although collective violence represents a significant public health concern, a limited number of longitudinal studies have addressed this topic, with no systematic reviews focusing on posttraumatic stress symptom (PTSS) trajectories. The present systematic review and meta-analyses examined PTSS prevalence and trajectories after exposure to collective violence. A systematic literature search across six databases (APA PsycInfo, APA PsycArticles, PSYINDEX, MEDLINE, ERIC, and PubMed) identified 771 studies that were screened for the following eligibility criteria: exposure to collective violence, adult sample, longitudinal design, PTSS assessment using validated measures, PTSS trajectories estimated using latent growth modeling, and report sample prevalence rate for each trajectory. Ten studies met the criteria, and five meta-analyses were performed to assess the overall prevalence of each trajectory. Most included studies (63.6%) identified four trajectories, characterized as low-stable, high-stable, decreasing, and delayed-worsening. The low-stable trajectory was the modal response, with a pooled prevalence of 58.0%, 95% CI [51.0, 65.0]. The high-stable prevalence was 7.0%, 95% CI [4.0, 19.0]; the decreasing trajectory was 13%, 95% CI [9.0, 17.0]; and the delayed-worsening trajectory was 8.0%, 95% CI [5.0, 10.0]. A fifth trajectory, moderately stable, had a prevalence of 19.0%, 95% CI [9.0, 29.0]. The trajectory models robustly identified clinically relevant patterns of response to collective violence, offering a contribution to the literature and a starting point for future research. Further studies are needed, as a better comprehension of symptom trajectories after collective violence events has important clinical and public health implications.