Abstract
First responders are at risk for developing symptoms of posttraumatic stress disorder (PTSD). Little is known about the risk factors for developing PTSD during a years-long period after complex mass disasters. To explore the long-term course of PTSD symptoms and to identify risk factors and their relative association with PTSD among first responders dispatched to the 2011 Japanese earthquake, tsunami, and nuclear disaster. This 6-year, large, prospective cohort study was part of a continuous longitudinal study of Japan Ground Self-Defense Force first responders. The data were collected at 1, 6, 12, 24, 36, 48, 60, and 72 months after mission completion from 2011 to 2017. Of approximately 70 000 eligible participants, 56 388 were enrolled in this study. Data were analyzed from 2017 to 2020. Stress exposures owing to personal or professional disaster experience (eg, duties with body recovery or radiation exposure risk) and working conditions (eg, deployment length, postdeployment overtime work). The Impact of Event Scale-Revised score assessed PTSD symptoms; scores of at least 25 were defined as probable PTSD. Cox proportional hazards regression models assessed the risk factors for incidence of probable PTSD. Among the 56 388 participants, 97.1% were men, and the median age at enrollment was 34 (range, 18-63) years. A probable PTSD rate was 2.7% at 1 month and showed a downward trend in the first year and a subsequent plateau. The cumulative incidence of probable PTSD was 6.75%. The severity of PTSD symptoms demonstrated a high degree of rank-order stability over time. Rather than professional disaster experience, sociodemographic factors and working conditions were independently associated with the incidence of probable PTSD: personal experience of the disaster (hazard ratio [HR], 1.96; 95% CI, 1.72-2.24), deployment length of at least 3 months (HR vs <1 month, 1.75; 95% CI, 1.52-2.02), increased age (HR for ≥46 vs ≤25 years, 2.28; 95% CI, 1.79-2.92), and postdeployment overtime work of at least 3 months (HR vs little to none, 1.61; 95% CI, 1.39-1.87). Given these findings, in the future, first responders' PTSD symptoms might be mitigated by shortening deployment length, avoiding postdeployment overtime work, and paying special attention to the needs of personnel with personal experience of the disaster or older age. Efforts to alleviate responders' initial symptoms will be required.
Highlights
On March 11, 2011, a magnitude 9.0 giant earthquake struck Japan and subsequently caused tsunamis and a level 7 critical nuclear accident according to the International Nuclear and Radiological Event Scale.[1]
Rather than professional disaster experience, sociodemographic factors and working conditions were independently associated with the incidence of probable posttraumatic stress disorder (PTSD): personal experience of the disaster, deployment length of at least 3 months (HR vs
The comparison of baseline PTSD symptoms between participants with and without follow-up after a 2-year survey period is shown in eTable 1 in the Supplement, indicating that participants who were subject to attrition had more PTSD symptoms than those continuing to participate
Summary
On March 11, 2011, a magnitude 9.0 giant earthquake struck Japan and subsequently caused tsunamis and a level 7 critical nuclear accident according to the International Nuclear and Radiological Event Scale.[1]. Disaster relief missions included rescue duties, body recovery operations of approximately 10 000 human remains, and humanitarian support in the areas with a risk of radiation exposure.[3]. First responders involved in disaster relief fulfill their duties amid life-threatening and potentially traumatic situations. They are often exposed to overwhelming emotional reactions from those affected by the disaster and their families, which could lead to secondary traumatic stress, compassion fatigue,[4] and vicarious traumatization.[5] As a result, first responders could manifest posttraumatic stress symptoms, and some responders will develop stress-related disorders, such as posttraumatic stress disorder (PTSD).[6] A meta-analysis of studies on first responders[7] estimated the incidence of full-blown PTSD among them at approximately 10%. Major risk factors for PTSD in first responders usually relate to duty, such as earlier start date or longer duration of time working at a disaster site,[8,9,10,11] exposure to human remains,[12,13,14] or nuclear disaster response.[15,16] Other risk factors include female sex,[10,17,18] direct personal experience of the disaster,[8,9,10,19] low social support,[17,18,19] and postdisaster life stressors, such as job loss.[8,9,17,18,19]
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