Risk and resilience in trajectories of post-traumaticstress symptoms among first responders after the2011 Great East Japan Earthquake : 7-yearprospective cohort study

Background:

First responders to disasters are at risk of developing post-traumatic stress disorder (PTSD). The trajectories of post-traumatic stress symptom severity differ among individuals, even ifthey are exposed to similar events. These trajectories have notyet been reported in non-Western first responders.

Aims:

We aimed to explore post-traumatic stress symptom severitytrajectories and their risk factors in first responders to the 2011Great East Japan Earthquake (GEJE)–a historically large earth-quake that resulted in a tsunami and a nuclear disaster.

Method:

A total of 55 632 Japan Ground Self-Defense Force (JGSDF) per-sonnel dispatched to the GEJE were enrolled in this 7-year lon-gitudinal cohort study. PTSD symptom severity was measuredusing the Impact of Event Scale-Revised. Trajectories wereidentified using latent growth mixture models (LGMM). Ninepotential risk factors for the symptom severity trajectories wereanalysed using multinomial logistic regression.

Results:

Five symptom severity trajectories were identified:‘resilient’(54.8%),‘recovery’(24.6%),‘incomplete recovery’(10.7%),‘late-onset’(5.7%), and‘chronic’(4.3%). The main risk factors forthe four non-resilient trajectories were older age, personal dis-aster experiences and working conditions. These working con-ditions included duties involving body recovery or radiationexposure risk, longer deployment length, later or no post-deployment leave and longer post-deployment overtime.

Conclusions:

The majority of first responders to GEJE were resilient anddeveloped few or no PTSD symptoms. A substantial minorityexperienced late-onset and chronic symptom severity trajec-tories. The identified risk factors can inform policies for preven-tion, early detection and intervention in individuals at risk ofdeveloping symptomatic trajectories.