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 if they are exposed to similar events. These trajectories have not yet been reported in non-Western first responders.

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

A total of 55 632 Japan Ground Self-Defense Force (JGSDF) personnel dispatched to the GEJE were enrolled in this 7-year longitudinal cohort study. PTSD symptom severity was measured using the Impact of Event Scale-Revised. Trajectories were identified using latent growth mixture models (LGMM). Nine potential risk factors for the symptom severity trajectories were analysed using multinomial logistic regression.

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 for the four non-resilient trajectories were older age, personal disaster experiences and working conditions. These working conditions included duties involving body recovery or radiation exposure risk, longer deployment length, later or no post-deployment leave and longer post-deployment overtime.

The majority of first responders to GEJE were resilient and developed few or no PTSD symptoms. A substantial minority experienced late-onset and chronic symptom severity trajectories. The identified risk factors can inform policies for prevention, early detection and intervention in individuals at risk of developing symptomatic trajectories.

灾害的第一响应者有患上创伤后应激障碍 (PTSD) 的风险。创伤后应激症状严重程度的轨迹因人而异，即使他们暴露于类似事件。这些轨迹尚未在非西方急救人员中报告。

我们旨在探索 2011 年东日本大地震 (GEJE) 的急救人员的创伤后应激症状严重程度轨迹及其风险因素——这是一场历史上导致海啸和核灾难的大地震。

这项为期 7 年的纵向队列研究共招募了 55632 名日本陆上自卫队 (JGSDF) 派遣到 GEJE 的人员。创伤后应激障碍症状的严重程度是使用修订的事件量表的影响来衡量的。使用潜在生长混合模型 (LGMM) 确定轨迹。使用多项逻辑回归分析了症状严重程度轨迹的九个潜在危险因素。

确定了五个症状严重程度轨迹：“有弹性”（54.8%）、“恢复”（24.6%）、“不完全恢复”（10.7%）、“迟发”（5.7%）和“慢性”（4.3%） . 四种非弹性轨迹的主要风险因素是年龄、个人灾难经历和工作条件。这些工作条件包括涉及身体恢复或辐射暴露风险的职责、较长的部署时间、较晚或没有部署后假期以及较长的部署后加班时间。

GEJE 的大多数第一响应者具有复原力，很少或没有出现 PTSD 症状。相当一部分人经历了迟发性和慢性症状严重程度的轨迹。确定的风险因素可以为有发展症状轨迹风险的个人的预防、早期发现和干预政策提供信息。