Posttraumatic Stress Dynamics and 15-Year Persistence in Great East Japan Earthquake Survivors
Xue Li, Hitomi Usukura, Yusuke Utsumi, Moe Seto, Atsushi Sakuma, Kazuho Tomimoto, Terufumi Machida, Yumiko Hamaie, Natsuko Kobayashi, Hiroshi Komatsu, Saya Kikuchi, Shinichi Kuriyama, Naoki Nakaya, Atsushi Hozawa, Yasuto Kunii, Hiroaki TomitaImportance
Long-term persistence of posttraumatic stress reactions (PTSRs) is a major public health challenge, yet early prognostic markers for decadal outcomes remain poorly characterized. Specifically, the importance of early symptom fluctuations compared with initial cross-sectional severity is not well understood.
Objective
To determine whether early postdisaster symptom dynamics within 1 year are associated with persistent, clinically meaningful PTSRs 15 years after the 2011 Great East Japan Earthquake (GEJE).
Design, Setting, and Participants
This 15-year prospective longitudinal cohort study (2011-2025) included residents of Shichigahama, Miyagi, Japan, aged 20 years or older, who experienced disaster-certified housing destruction after the GEJE.
Exposures
Early symptom dynamics (2011-2012) based on Impact of Event Scale–Revised (IES-R) scores and classified as (1) high-escalating (IES-R score ≥25 and increasing), (2) high-improving (IES-R score ≥25 and nonincreasing), and (3) nonpersistent early (IES-R score <25 at either wave).
Main Outcomes and Measures
The primary outcomes were persistent, clinically meaningful PTSRs (IES-R score ≥25) at 15 years. Multivariable logistic regression with 40-fold multiple imputation was used to estimate adjusted odds ratios (aORs).
Results
Among 1291 participants (685 women [53.1%]; mean [SD] age, 53.9 [16.6] years), group-based trajectory modeling of IES-R scores (2011-2025) identified 5 distinct PTSR patterns. At 15 years, 14.7% of participants (190 participants) had clinically meaningful PTSRs. Symptom escalation was most frequent during the first-to-second year interval compared with all subsequent periods. This trend remained consistent even under stringent escalation criteria (>5-point increase). The high-escalating pattern was the one most associated with 15-year persistence (aOR, 5.31; 95% CI, 3.85-7.32). The prognostic model incorporating early dynamics demonstrated improved discrimination (area under the curve [AUC], 0.756; 95% CI, 0.717-0.763) compared with models using baseline symptom severity alone (AUC, 0.608; 95% CI, 0.600-0.612) or delayed single-point assessments (AUC, 0.726; 95% CI, 0.663-0.738).
Conclusions and Relevance
In this 15-year cohort study of GEJE survivors, symptom escalation during the first-to-second year interval was identified as the most prevalent pattern and was a factor associated with long-term persistent PTSRs. Because early symptom dynamics offer superior prognostic accuracy compared with single-point assessments, these findings support a serial screening approach during the immediate postdisaster period to optimize risk stratification and early intervention strategies.