Trajectories and Determinants of Posttraumatic Stress in Disaster Survivors: A Group-Based Trajectory Modeling Study

Disasters can result in long-term posttraumatic stress (PTS), the trajectory of which may vary widely among individuals. Although typical patterns of PTS have been suggested in prior studies, scholarly consensus on pattern classification and related factors remains limited.

This study was developed to identify the general patterns of PTS in disaster survivors over time using trajectory modeling and to examine the characteristics of each trajectory group.

A secondary analysis was conducted on original data from the Long-term Survey on the Change of Life of Disaster Victims implemented by the National Disaster Management Research Institute of South Korea. PTS trajectories with similar trends were grouped together using Group-Based Trajectory Modeling (GBTM), and the characteristics of each trajectory group were identified using multinomial logistic regression analysis.

The GBTM analysis identified four distinct PTS trajectory groups. Group 1, which captured the largest number of individuals, showed stable, low-level PTS over time (Group 1: resistance 66.1%, n = 698); Group 2 captured individuals with rising PTS trajectories over time (Group 2: delayed, 11.1%, n = 101); Group 3 captured individuals with an initially high level of PTS and a trajectory of recovery over time (Group 3: recovery, 16.4%, n = 161); and Group 4, representing the smallest number of individuals, showed stable, high-level PTS over time (Group 4: chronic, 6.4%, n = 65). The adjusted analysis showed that Groups 2-4 differed from Group 1 in several variables, including resilience and disaster-related harm variables.

The representative trajectories of PTS in disaster survivors and their associated characteristics were identified in this study. The findings indicate individuals with initially low levels of PTS may experience rising symptom severity (Group 2) and that those with initially high levels of PTS may face slower-than-expected recoveries (Group 4). Based on the findings, tailored interventions accounting for the group-specific risk factors identified in this study are needed.