Epidemiologic psychiatric studies on post-disaster impact among Chi-Chi earthquake survivors in Yu-Chi, Taiwan
Frank Huang-Chih Chou, MD, MS, PhD, Department of Community Psychiatry, Kai-Suan Psychiatric Hospital, 130, Kai-Suan 2nd Road, Lingya District, Kaohsiung, Taiwan. Email: firstname.lastname@example.org
Abstract The aim of the present study was to survey a cohort population for the risk factors of post-traumatic stress disorder (PTSD) and major depression, and the prevalence of different psychiatric disorders at 6 months and 2 and 3 years after a major earthquake. The Disaster-Related Psychological Screening Test (DRPST), part I, and the Mini-International Neuropsychiatric Interview (MINI) were, respectively, administered by trained interviewers and psychiatrists in this community-interview program. The prevalence of PTSD decreased from 8.3% at 6 months to 4.2% at 3 years after the earthquake. Suicidality increased from 4.2% at 6 months and 5.6% at 2 years to 6.0% at 3 years after the earthquake; drug abuse/dependence increased from 2.3% at 6 months to 5.1% at 3 years after the disaster. The risk factors for PTSD and major depression in various post-disaster stages were determined. Earthquake survivors had a high percentage of psychiatric disorders in the first 2 years, and then the prevalence declined. Following the devastation caused by the Chi-Chi earthquake, it is important to focus on treating symptoms of major depression and PTSD and eliminating the risk factors for both of these disorders in survivors to avoid the increase in suicidality.
The devastating Chi-Chi earthquake, so named because of the location of the epicenter near Chi-Chi Township in Nantou County, Taiwan, measured 7.3 on the Richter scale and struck in the early morning of 21 September 1999. According to the statistics of the National Fire Administration and the Ministry of the Interior as of 11 October 1999, 2329 people died and 8722 were injured as a result of this catastrophe.1 Earthquakes have been responsible for some devastating natural disasters in the 20th century.2–5 Unfortunately, in the early 21st century, a catastrophic earthquake in the Indian Ocean, registering 9.0 on the Richter scale, triggered a tsunami that resulted in the deaths of several hundred thousand people in South and South-east Asia, reminding us of the importance of disaster psychiatry. The impact can be extensive and severe, and the effects often persist long after the traumatic events. Following the Chi-Chi earthquake, the authors anticipated that the psychologicalrehabilitation programs of Yu-Chi Township, near the epicenter of earthquake, would provide an opportunity to study the impact of a natural disaster on survivors, in general, and particularly on the Taiwanese population.6
A PubMed search found 20 papers, published as of June 2006, related to the development of psychiatric problems after the Chi-Chi earthquake, including (i) the prevalence and risk factors of psychiatric disorders in different groups;1,6–18 (ii) establishment of a screening test;5,19 (iii) quality of life in survivors;1,11–13,20 (iv) suicide rate following the earthquake;20,21 and (v) others.22 The different study designs showed the disparities in prevalence of post-traumatic stress disorder (PTSD) after the earthquake, attributed mainly to the magnitude of the quake and the number of casualties, differences in the criteria for case definition and methods of case identification, and different intervals of follow up after the quake. For example, the studies reported prevalence rates for PTSD ranging from 7.9% to 37% in Taiwan after the 1999 earthquake.1,6–11
Research on the short-term psychiatric effects following earthquakes found an increased prevalence of psychiatric disorders,1,4,6,8–10,21 suicide rates,23,24 and decreased quality of life of survivors.1,7,11,20 Two risk factors for PTSD were being physically injured and experiencing the death of a close family member with whom they had lived.9 In addition, an individual's personality traits and life adjustment before the disaster had a dominant predictive power for psychological distress.17
PTSD can be triggered by a variety of traumatic events and is strongly associated with all other examined mental disorders, especially major depression.6 The prevalence of psychiatric disorders such as PTSD or major depression suddenly increased after the impact of the earthquake. Although these survivors suffer psychological impairments from disaster impact, most of them will recover from the event soon afterward. However, a few will suffer from psychiatric disturbances for a longer period. They must be treated and followed up for a long time afterward. It seems reasonable that studying post-disaster behavior may prove helpful in evaluating the requirements of immediate psychiatric manpower.6,24 However, few long-term follow-up data on the long-term effects caused by the disaster are available.1,4,12,13 Therefore, we conducted a 3-year follow-up survey on the prevalence of different psychiatric disorders in the study population; depression and PTSD were found to be the most common disaster-related psychiatric diagnoses and were strongly associated with each other.1,6,7,20 We also evaluated the risk factors for PTSD and major depression 6 months, 2 years, and 3 years after the earthquake. Some studies found a gradually increasing suicide rate after earthquake.23,24 We wanted to determine the suicide rate over time in the present study population and the related psychiatric effects. In addition, we wanted to understand the long-term trends and different risk factors for major depression and PTSD after a major catastrophe, which were not reported in the previous studies.
Formerly consisting of 13 villages, Yu-Chi Township in Nantou County was the epicenter of the Chi-Chi earthquake. There were approximately 500–850 residents, over 16 years of age, in each village at the time of the earthquake. Because Yu-Chi Township was near the epicenter, all residents were deemed equally exposed to the disaster. There are several benefits to selecting Tong-Chi village of Yu-Chi township for cluster sampling: (i) there were approximately 700 residents over 16 years of age, which fit the distribution of Yu-Chi township's residents; (ii) a team of specially trained, senior psychiatrists set up a temporary clinic at Tong-Chi Village immediately after the earthquake occurred (the study was conducted after a good rapport was established between the research team members and residents 4–6 months after the earthquake;6 this good relationship increased the response rate); and (iii) a total of 216 residents were included in the all three study periods (6 months, 2 years, and 3 years after the earthquake).
This paper is part of a prospective naturalistic study on the impact of a catastrophic earthquake on survivors. Taking the migration of the earthquake survivors into consideration, the adjusted response rates in the three periods were 73.4%,6 79.9%,1 and 70.2%, respectively.12 We also analyzed data from the 216 individuals who responded to all three surveys (response rate 35.8%) in the present paper.
Five psychiatrists and two public health professionals designed and validated the Disaster-Related Psychological Screening Test (DRPST) to collect background information from residents and to find psychological symptoms resulting from disaster-related psychiatric disorders.5 The DRPST has two parts. The first part was used to compile background information, including date of birth, gender, education, marital status, extent of physical injury, self-reported memory impairment, family loss, and economic loss following the earthquake. The second part is a scale based on DSM-IV symptoms, which was validated by psychiatrists when compared with the Mini-International Neuropsychiatric Interview (MINI) in the same population. We used the first part to evaluate the risk factors of psychiatric disorders.
Psychiatrists also used the Taiwan version of MINI (based on the 5.0 English version) to assess respondents for the prevalence of different psychiatric disorders. This relatively short instrument was designed to provide enough diagnostic information to make good clinical decisions while investigating the 17 major Axis I diagnoses (including PTSD, suicidality within 1 month, and current major depression within 2weeks). Among the strengths of the MINI are brevity, simplicity, clarity, high sensitivity and specificity, and ease of administration.25 PTSD, current major depression, and suicidality were included in MINI. Priority was given to the identification of current disorders, with no attempt made to identify the diagnostic subtypes of psychotic disorders.1 Originally, it was developed to provide a short diagnostic structured interview compatible with the DSM-IV (used for the present study), and its question formulations are similar to those of the Composite International Diagnostic Interview (CIDI).5 In addition to these advantages, the authors felt that the MINI seemed to be useful because of its structured nature for use in clinical psychiatric research settings.6
The Taiwan version of MINI was translated by several senior psychiatrists and retranslated into English, which was copyrighted to the Taiwan Society of Psychiatry by the original author. There was specialist validity of the Taiwan version of MINI and lack of other validity due to the lack of validity and reliability of the Taiwan version of the CIDI. However, the trained psychiatrist interviewing residents completed an interrater reliability test and the κ value was 0.75, Z score = 13.22.26
The details of this training program were reported previously.5,6 Because the validation of DRPST was established at second survey,5,26 some variables (e.g. ‘Family financial burden and social network change’) were not measured at first survey. We used these variables that were measured at the second survey. The research assistants used the first part of DRPST13 to gather basic information and related data on risk factors from all residents ≥16 years of age, which was analogous to information of non-respondents derived from local government records. Psychiatrists interviewed these residents using the MINI in the three study periods. The purpose of the research project was explained in detail to each resident during the home visit. If the residents refused to participate after being informed about the research project, only their demographic information was collected, using an appropriate questionnaire. Informed consent was obtained from all respondents as well as approval from the local government authorities and the Department of Health of the Executive Yuan. The Institutional Review Board oversaw the study and a human studies review in Kai-Suan psychiatric hospital. We compared the prevalence of PTSD and other psychiatric disorders 6 months, 2 years, and 3 years after the earthquake, and the psychosocial risk factors of PTSD or major depression groups were compared with that of the normal population.
Demographic data for total responding residents were compared using the χ2 test (2 × n nominal data) with the Yates correction (2 × 2 nominal data). Odds ratios (with 95% confidence interval) were used to compare the prevalence of psychiatric disorder, PTSD, and suicidality comorbidity. In addition, we used multiple logistic regressions to evaluate the risk factors of major depression and PTSD over 3 years. All the data were analyzed using SPSS version 10.0 software (SPSS, Chicago, IL, USA).
There were 216 respondents (99 men, 117 women) followed up in all three periods. The most common educational level was primary school level or below. No statistically significant differences were found in marital status, gender, and age between responders and non-responders.
Prevalence of psychiatric diseases
Six months after the earthquake, the prevalence rates were 11.6% for current major depression and 8.3% for PTSD. The prevalence of PTSD decreased to 4.2% at 3 years after the earthquake despite there being an increase from 8.3% at 6 months after the earthquake to 9.7% at 2 years after the event. The prevalence of current major depression decreased to 6.9% at 2 years and to 6.5% at 3 years after earthquake. In contrast, the prevalence of suicidality gradually increased, from 4.2% at 6 months after the earthquake and 5.6% at 2 years to 6.0% at 3 years after the earthquake. Drug abuse/dependence gradually increased from 2.3% at 6 months to 2.3% and 5.1% at 2 and 3 years after the earthquake, respectively (Table 1).
Table 1. Prevalence of psychiatric disorders after the Chi-Chi Earthquake (fixed cohort, n = 216)
|6 months later|
|PTSD|| || ||0.728|| ||0.093|
| Present||18||3 (17)|| ||2 (11)|| |
| Absent||198||18 (9)|| ||7 (4)|| |
|Current major depression|| || ||0.110|| ||0.099|
| Present||25||4 (16)|| ||1 (4)|| |
| Absent||191||11 (6)|| ||13 (7)|| |
|Suicidality|| || ||0.581|| ||0.454|
| Present||9||4 (44)|| ||3 (33)|| |
| Absent||207||8 (4)|| ||10 (5)|| |
|Alcohol abuse/dependence|| || ||0.727|| ||1.000|
| Present||9||6 (67)|| ||5 (56)|| |
| Absent||207||5 (2)|| ||5 (2)|| |
|Drug abuse/dependence|| || ||1.000|| ||0.180|
| Present||5||0 (0)|| ||1 (20)|| |
| Absent||211||5 (2)|| ||10 (5)|| |
|Dysthymic disorder|| || ||0.607|| ||1.000|
| Present||10||1 (10)|| ||0 (0)|| |
| Absent||206||6 (3)|| ||10 (5)|| |
|Panic disorder|| || ||0.625|| || |
| Present||3||0 (0)|| ||0 (0)|| |
| Absent||213||1 (0.5)|| ||0 (0)|| |
|General anxiety disorder|| || ||1.000|| ||1.000|
| Present||6||0 (0)|| ||0 (0)|| |
| Absent||210||6 (3)|| ||6 (3)|| |
We found that the prevalence of suicidality increased 3 years after this earthquake and evaluated the relationship between suicidality and the different psychiatric disorders; survivors with current major depression had the highest suicidality compared with any other psychiatric diagnosis (Table 2). The analyses of suicidality associated with current major depressive episode, drug dependence/abuse, and current PTSD were also statistically significant.
Table 2. Psychiatric disease associated with suicidality after the Chi-Chi Earthquake
|Current major depression‡|
| Yes||4 (44.4)||21 (10.1)||7.09†||1.77–28.45||4 (33.3)||11 (5.4)||8.77†|| 2.29–33.68||7 (53.8)||7 (3.4)||32.67†|| 8.68–122.98|
| No||5 (55.6)||186 (89.9)|| || ||8 (66.7)||193 (94.6)|| || ||6 (46.2)||196 (96.6)|| || |
| Yes||1 (11.1)||17 (8.2)||1.40||0.17–11.84||2 (16.7)||19 (9.3)||1.95||0.40–9.55||3 (23.1)||6 (3.0)||9.85†||2.14–45.24|
| No||8 (88.9)||190 (91.8)|| || ||10 (83.3)||185 (90.7)|| || ||10 (76.9)||197 (97.0)|| || |
| Yes||1 (11.1)||8 (3.9)||3.11||0.35–27.94||0 (0.0)||11 (5.4)||–||–||1 (7.7)||9 (4.4)||1.80||0.21–15.37|
| No||8 (88.9)||199 (96.1)|| || ||12 (100.0)||193 (94.6)|| || ||12 (92.3)||194 (95.6)|| || |
| Yes||0 (0.0)||5 (2.4)||–||–||0 (0.0)||5 (2.5)||–||–||3 (23.1)||8 (3.9)||7.31†||1.68–31.84|
| No||9 (100.0)||202 (97.6)|| || ||12 (100.0)||199 (97.5)|| || ||10 (76.9)||195 (96.1)|| || |
Risk factors of PTSD and major depression
Table 3 shows the risk factors of PTSD in respondents in three respective stages. ‘Grief due to family loss’ seemed to have a greater risk of leading to PTSD in all three respective stages. A greater risk of developing PTSD was found in responders reporting a ‘family financial burden’ at 6 months after the earthquake, in responders with ‘sleep disturbance’ 2 years after the earthquake, and in those with a ‘social network change’ 3 years after the earthquake.
Table 3. Significant predictors of PTSD after the Chi-Chi Earthquake by multiple logistic regression
|Family financial burden (Y/N)‡||3.827†||1.334–10.978||2.498||0.800–7.798||1.117||0.228–5.468|
|Severe house damage (Y/N)§||1.088||0.357–3.316||2.552||0.491–13.273||3.110||0.301–32.173|
|Social network change (Y/N)¶||0.413||0.048–3.532||3.116||0.862–11.255||7.210†||1.246–41.699|
|Grief due to family loss (Y/N)††||3.905†||1.159–13.154||6.464†||1.727–24.195||7.432†||1.352–40.852|
|Sleep disturbance (Y/N)||1.143||0.398–3.285||5.152†||1.450–18.300||2.864||0.432–18.998|
Table 4 shows the risk factors of major depression in different stages. The respondents with ‘sleep disturbance’ seemed to have a greater risk of developing major depression 2 and 3 years after the earthquake.
Table 4. Significant predictors of major depression after the Chi-Chi Earthquake by multiple logistic regression
|Family financial burden (Y/N)‡||1.485||0.600–3.674||0.358||0.056–2.276||1.110||0.311–3.958|
|Severe house damage (Y/N)§||1.722||0.628–4.721||12.080||0.763–191.143||1.875||0.345–10.201|
|Social network change (Y/N)¶||1.593||0.449–5.645||4.896||0.944–25.401||0.485||0.081–2.884|
|Grief due to family loss (Y/N)††||1.187||0.350–4.022||1.773||0.228–13.805||1.637||0.279–9.606|
|Sleep disturbance (Y/N)||1.863||0.756–4.592||30.244†||4.855–188.420||8.222†||2.056–32.884|
This is one of a few epidemiologic studies of survivors' psychiatric disorders and risk factors following a natural disaster. We believe this study has several strengths: (i) our research teams followed up these village residents for 3 years and helped them with mental rehabilitation, which reduced the difficulty of performing research; (ii) all diagnoses using the MINI were made by psychiatrists; (iii) our results involve long-term post-disaster effects, which were previously unmeasured by other research teams; and (iv) the method of the present study was cluster sampling, that is, sampling of the residents of a village from the Yu-Chi Township. Many studies, including those conducted in Taiwan, found diverse degrees of psychiatric morbidity and comorbidity following earthquakes.1,4–7,11,15–17,20,21 Several investigators have used hospitalized patients,10,27,28 patients staying in shelters,8 or a specific population, such as bereaved survivors,10 a geriatric population14,20 or adolescent survivors,9 to estimate the prevalence of psychiatric disorders after a disaster, which may result in a sampling bias.29
The present study, however, also has some limitations. First, the response rate in the present study was low and the demographics changed over time due to emigration, which introduced some sampling bias. However, there was a similar trend of prevalence of psychiatric disorders in the fixed cohort population compared with a dynamic population.1,6,12 Second, we had no data concerning the prevalence rates of PTSD and other psychiatric disorders in the present study population before the earthquake. Third, due to ethical issues, we evaluated and treated 84 patients who had psychiatric illnesses during an original assessment at that period after the earthquake in Yu-Chi township. We had followed up 60 patients 2 years later. Mental disorders and quality of life in earthquake survivors improved during long-term follow up.30 This may have decreased the prevalence of those with psychiatric disorders.
In the present cohort population followed up for 3 years, there were some changes in demographic data, current marital status, and educational level, which were partially due to an unbalanced distribution of economic and educational resources caused by post-disaster effects, resulting in the emigration of residents with a higher educational level, which contributed to the low response rate.
All of the prevalence rates of different disorders in different stages were not statistically significantly different, which might be due to the low response rate, but they showed clinical significance. Yang et al. found that the monthly suicide rate for Chi-Chi earthquake survivors was higher within 10 months of the disaster.24 Chou et al. found that Chi-Chi earthquake survivors were 1.46 times more likely than non-victims to commit suicide following this earthquake.23 They suggested that mental health programs or other preventive strategies might be more effective by specifically targeting victims rather than by simply targeting individuals living in areas affected by the disaster. Because of the suicidality and drug abuse/dependency increases 3 years after the earthquake, similar to the findings of Chou et al.23 and Yang et al.,24 we suggest that survivors should be monitored for more than 3 years after the disaster to avoid the deterioration of their psychiatric disorders or increase in suicide rate.
Many psychiatric disorders are associated with suicidality. According to the present data suicidality tended to be higher, especially in survivors with major depression, PTSD, or drug dependence/abuse. Other possible reasons were financial problems. In suicide prevention we should focus on both PTSD and major depression, according to the results of the present study. The residents living in the earthquake area who did not have thoughts of suicide might have been assisted by the economic resources provided by the government in the first 2 years after earthquake. Therefore, the residents did not have to worry about the economic aftermath of the disaster. This result was similar to that of the Wang et al. study, which found fewer prevalent psychiatric problems in the severe disaster-ravaged area that received more economic aid than in areas receiving less assistance.4 However, the economic resources provided by the government were reduced 3 years after the earthquake, and the residents then became concerned about the economic problems because of lack of resources, unemployment, and economic setbacks in recent years. Consequently, the prevalence of suicide may have increased gradually due to lack of economic aid.
The risk factors for PTSD included ‘grief due to family loss’ in all three stages after the earthquake. There were some differences each year after the earthquake due to various individualized rehabilitation outcomes, the long-term disaster effects, and the emigration of high-function residents. The residents tended to have PTSD because they did not have sufficient financial resources 6 months after the earthquake. Three years afterward, the residents tended to have PTSD because of changes in their social networks. This finding was in accord with previous reports.1,6,7,20 When we checked the risk factors of major depression, we found that ‘sleep disturbance’ was statistically significant 2 and 3 years after the disaster. We did not find other statistically significant risk factors. There might be some explanations. First, the total case numbers were few and the statistical power was insufficient. Second, major depression is not specific to the impact of the earthquake; that is, major depression was triggered by other psychosocial stressors and was not extensively specified in its relationship to the earthquake. In our findings, ‘sleep disturbance’ was highly related to major depression in this follow-up study. There are several possible explanations for these highly positive correlations. Sleep disturbance is one of the diagnostic criteria of major depression. Most respondents with major depression might not have received effective treatment;30 therefore, they continued to have persistent depression. Third, the low response rate resulted in selection bias.
Although, for most individuals, changes in emotional, cognitive, behavioral, and biologic states are mostly transitory after a catastrophe, the psychological trauma may persist much longer in certain victims, the psychological profiles of whom are often altered given their vivid and repetitive recalling of traumatic events.6,11,20 Wang et al. showed that prompt and effective post-disaster intervention might mitigate the impact of initial exposure and reduce the probability of PTSD occurrence.4 A lower PTSD incidence in the high-exposure groups than in low-exposure ones was demonstrated when more emergency relief personnel arrived earlier or stayed longer to help the survivors deal with various post-disaster difficulties. These results suggest that there is a necessity to establish mental rehabilitation services after an earthquake. Based on our findings, we recommend evaluating and monitoring suicidality and drug abuse/dependence behavior in survivors for more than 3 years. Clinicians or public health nurses should assess the mental conditions of survivors with major depression who are prone to develop delayed-type PTSD and treat them actively to decrease risk factors of suicidality.
Earthquake survivors had a high percentage of psychiatric disorders. The prevalence of PTSD or major depression was higher in the first 2 years, then significantly decreased in the third year. Risk factors for PTSD and major depression in respondents in various post-disaster stages were determined. Clinical therapists should put an emphasis on survivors suffering from major depression and PTSD because they are at heightened risk for suicide. In addition, the respondents with drug dependence/abuse, past major depression, PTSD, and previous suicidal tendencies and those who are women are also at high risk compared to those without these disorders or tendencies.
The study was supported by grants NSC 91-2625-Z-010-001, NSC 92-2625-Z-280-001 and NSC 93-2625-Z-280-001-from the National Science Council, Republic of China.