Association of Postdisaster Depression and Posttraumatic Stress Disorder with Mortality among Older Disaster Survivors of the 2011 Great East Japan Earthquake and Tsunami

Abstract

Importance: Depression and posttraumatic stress disorder (PTSD) represent 2 common mental health sequelae of natural disasters. However, to date, no studies have examined whether postdisaster depression and PTSD are associated with increased risk of mortality among community-dwelling survivors of natural disasters. Objective: To assess whether postdisaster depression and PTSD were associated with mortality in older disaster survivors. Design, Setting, and Participants: In this cohort study, prospective data were retrieved from older Japanese adults in Iwanuma City, Miyagi Prefecture, which was directly affected by the 2011 Great East Japan Earthquake and Tsunami. The baseline was established 7 months before the disaster (August 2010), and follow-up surveys were conducted approximately 2.5 years afterward (October 1, 2013, to January 31, 2014). Invitations were mailed to every citizen 65 years or older in Iwanuma City. Mortality data were obtained through March 4, 2017. Data analysis was performed from December 1, 2018, to June 30, 2019. Exposures: Postdisaster depression (Geriatric Depression Scale Short Form score ≥5) and PTSD (Screening Questionnaire for Disaster Mental Health PTSD subscale score ≥4) were measured in 2013. Main Outcomes and Measures: Mortality data were obtained by linkage to the national long-term care insurance database. Cox proportional hazards regression models were adjusted for predisaster sociodemographic characteristics, health behaviors, social cohesion, predisaster depression, and disaster experiences. Results: The response rate for the baseline survey was 59.0% (5058 of 8567 individuals), and the follow-up rate was 82.1% (3594 of 4380 eligible respondents). A total of 2965 individuals (mean [SD] age, 73.4 [6.2] years; 1621 [54.7%] female) participated in the study. The mean (SD) follow-up since the 2013 survey was 3.3 (0.5) years. Overall, 974 (32.8%) reported postdisaster depression and 747 (25.2%) reported PTSD. In adjusted models, depression was associated with more than double the risk of mortality (hazard ratio, 2.29; 95% CI, 1.54-3.42); PTSD was not associated with increased risk of mortality (hazard ratio, 1.10; 95% CI, 0.73-1.64). When evaluating the association of the 4-category comorbid depression and PTSD variable with mortality, survivors with depression only (HR, 2.24; 95% CI, 1.43-3.49) as well as those with comorbid depression and PTSD (HR, 2.54; 95% CI, 1.50-4.27) were at increased risk of death during the follow-up period compared with those with neither depression nor PTSD. Conclusions and Relevance: Depression, but not PTSD, was associated with mortality during 3.3 years of follow-up among older disaster survivors. These findings suggest that long-term mental health consequences of natural disasters may exist and that treating depression in older survivors of disasters may be beneficial..