Increase in short-term and long-term stress-associated mental illness after Jiji earthquake in Taiwan: A twenty-year longitudinal population-based cohort study (1999-2019).

Background: Earthquakes have caused profound physical and mental health impacts in human history. The Jiji earthquake, which had a magnitude of 7.6 on the Richter scale, occurred on 21 September 1999 in Taiwan. A close follow-up on the mental health status of affected adults after major natural disasters to construct the short-term and long-term risk and prevalence of stress-associated mental illnesses has not been performed by using the nationwide health databases.

Methods: This population-based cohort study included 468,804 adults affected by Jiji earthquake spanning from 2000 to 2019 who were matched at a 1:4 ratio with unaffected individuals based on age and sex (n = 1,875,216). Employing a subdistribution hazard regression analysis, we assessed the incidence of sleep, anxiety, and depressive disorders after Jiji earthquake. Corrections for multiple comparisons were carried out using the Benjamini-Hochberg procedure.

Results: Affected adults experienced an increased incidence of short-term (approximately twice) stress-associated psychiatric disorders. The risk of the post-traumatic stress disorder (PTSD) is significantly higher in the affected adults (40-64 years: aSHR: 92.0; ≥65 years: aSHR: 96.7, p < 0.0001). Middle-aged (aged 40-64 years) male adults presented with significantly more short-term (< one year) and long-term (up to 20 years) stress-related mental illnesses, i.e., insomnia, anxiety, and depressive disorders, than individuals in the control group.

Conclusions: An earthquake has significant short and long-term effects on sleep quality, anxiety, and depressive disorders in affected adults. Optimal short and long-term close monitoring is needed to deploy medical resources and socioeconomic support to relieve mental stress burdens.