# Screening for Psychological Distress, Disaster-Related Experiences, and Newly Developed Mental Disorders among Residents Affected by the Great East Japan Earthquake: Implications for Suicide Prevention

## TL;DR

This study shows that combining the K6 psychological distress scale with factors like PTSD and income loss improves suicide risk prediction after disasters.

## Contribution

The study identifies specific factors that enhance the K6 scale's accuracy in predicting suicide after disasters.

## Key findings

- Combining K6 with PTSD and income loss improved suicide prediction accuracy.
- Disaster-related stress symptoms increased the predictive power of the K6 scale.
- The K6 alone had lower accuracy compared to combinations with other factors.

## Abstract

This study aimed to evaluate the accuracy of screening using the six-item Kessler Psychological Distress Scale (K6) for suicide death after the Great East Japan Earthquake (GEJE) in combination with binge drinking, diagnosed history of mental disorders, disaster-related experiences, disaster stress symptoms, sleep status, and social network, which were used in the practical settings of disaster-related mental health services.

This prospective cohort study spanned the period from 2013 to 2021. Among the Tohoku Medical Megabank Project sample, 27,335 affected residents and 61,157 residents living within the disaster-stricken area (i.e., those who experienced partial or no house damage and did not evacuate even if they lived in the disaster-stricken area) of the GEJE were analyzed using receiver operating characteristic curve (ROC) analyses of the K6 score in combination with the following related factors: binge drinking, disaster experiences (loss of a family member, relatives and friends, and decrease in income), disaster-related stress symptoms (recollection of disaster experiences, physical reactions due to recalling the disaster), diagnosed history of mental disorders (depression and post-traumatic stress disorder [PTSD]), sleep status, and social network.

In the ROC analyses, when the K6 score was combined with relevant variables, newly developed PTSD after the GEJE (area under the curve [AUC]: 0.878 [95% confidence interval (CI): 0.773-0.982]), disaster-related stress symptom of recollection of disaster experiences (AUC: 0.849 [95% CI: 0.714-0.985]), and decreased income (AUC: 0.835 [95% CI: 0.726-0.945] yielded higher AUCs than did the K6 score alone (AUC: 0.681 [95% CI: 0.567-0.794]).

When screening using K6 for suicide death, combining the K6 score with newly developed PTSD, recollection-related disaster stress symptoms, and decreased income could generate more accurate predictions of suicide after the disaster. We hope these findings will contribute to minimizing post-disaster suicide in the context of disaster-related mental health services. (297 words)