The importance of estimating selection bias on prevalence estimates shortly after a disaster

Evaluating the impact of Hazelwood mine fire event on students' educational development with Bayesian interrupted time-series hierarchical meta-regression

BACKGROUND

Environmental disasters such as wildfires, floods and droughts can introduce significant interruptions and trauma to impacted communities. Children and young people can be disproportionately affected with additional educational disruptions. However, evaluating the impact of disasters is challenging due to difficulties in establishing studies and recruitment post-disasters.

OBJECTIVES

We aimed to (1) develop a Bayesian model using aggregated school-level data to evaluate the impact of environmental disasters on academic achievement and (2) evaluate the impact of the 2014 Hazelwood mine fire (a six-week fire event in Australia).

METHODS

Bayesian hierarchical meta-regression was developed to evaluate the impact of the mine fire using easily accessible aggregated school-level data from the standardised National Assessment Program-Literacy and Numeracy (NAPLAN) test. NAPLAN results and school characteristics (2008-2018) from 69 primary/secondary schools with different levels of mine fire-related smoke exposure were used to estimate the impact of the event. Using an interrupted time series design, the model estimated immediate effects and post-interruption trend differences with full Bayesian statistical inference.

RESULTS

Major academic interruptions across NAPLAN domains were evident in high exposure schools in the year post-mine fire (greatest interruption in Writing: 11.09 [95%CI: 3.16-18.93], lowest interruption in Reading: 8.34 [95%CI: 1.07-15.51]). The interruption was comparable to a four to a five-month delay in educational attainment and had not fully recovered after several years.

CONCLUSION

Considerable academic delays were found as a result of a mine fire, highlighting the need to provide educational and community-based supports in response to future events. Importantly, this work provides a statistical method using readily available aggregated data to assess the educational impacts in response to other environmental disasters.

Non-linear Dynamic Shifts in Distress After Wildfires: Further Tests of the Self-Regulation Shift Theory

Worldwide exposure to explosive wildfires has become increasingly common. The psychological impact of these fires is substantial, demanding a deeper understanding of post-wildfire adaptation. This paper consists of two studies aiming to test self-regulation shift theory and its predicted non-linear shifts in distress using cusp catastrophe analyses. Study 1 tested a cusp catastrophe model on distress after the Waldo Canyon wildfire, Colorado (June, 2012). Results of study 1 showed that coping self-efficacy early after the wildfire was a significant bifurcation factor affecting when a shift in distress levels occurred from a lower state to an upper state. Perceived loss was a significant asymmetry controlling factor affecting the relative strength of each state. These findings indicate that a non-linear shift is more likely to occur at lower levels of coping self-efficacy and higher perceived loss. Study 2 tested the same model among survivors of several wildfires in California during 2017 and 2018. Results of study 2 confirmed the importance of coping self-efficacy again as a significant bifurcation factor. In this case, peritraumatic dissociation was found to be a significant asymmetry controlling factor instead of loss. These results indicate that an upward shift in distress occurs when coping self-efficacy is lower and peritraumatic dissociation is higher. Collectively, the combined findings suggest that coping self-efficacy is a pivotal variable consistent with self-regulation shift theory predictions. Intervention implications are discussed.

Non-participation and attrition in a longitudinal study of civilians exposed to the January 2015 terrorist attacks in Paris, France

BACKGROUND

Non-participation and attrition are rarely studied despite being important methodological issues when performing post-disaster studies. A longitudinal survey of civilians exposed to the January 2015 terrorist attacks in Paris, France, was conducted 6 (Wave 1) and 18 months (Wave 2) after the attacks. We described non-participation in Wave 1 and determined the factors associated with attrition in Wave 2.

METHODS

Multivariate logistic regression models were used to compare participants in both waves with those who participated in the first wave only. Analyses were performed taking the following factors into account: socio-demographic characteristics, exposure to terror, peri-traumatic reactions, psychological support, perceived social support, impact on work, social and family life, and mental health disorders. Characteristics of new participants in Wave 2 were compared with participants in both waves using a chi-square test.

RESULTS

Of the 390 persons who were eligible to participate in the survey, 190 participated in Wave 1 (participation rate: 49%). The most frequently reported reason for non-participation was to avoid being reminded of the painful event (32%, n = 34/105). In Wave 2, 67 were lost to follow-up, 141 people participated, of whom 123 participated in Wave 1 (re-participation rate: 65%) and 18 were new. Attrition in Wave 2 was associated with socio-demographic characteristics (age, French origin) and location during the attacks, but not with terror exposure or mental health disorders. Compared with those who participated in both waves, new participants declared less social and psychological support since the attacks.

CONCLUSIONS

Attrition at 6 months was not associated with exposure to terror or mental health disorders, which indicates that any bias in future analyses on IMPACTS on mental health outcomes will be limited. Our findings suggest the importance of adapting similar surveys for people of foreign origin and of improving strategies to avoid attrition of younger people, for example by using social media, peers, and the educational environment. The present study also revealed that a high level of exposure to terror and a lack of social and psychological support after a terrorist event could impede individuals' participation in similar surveys in the short term.

Different Trajectories of Prolonged Grief in Bereaved Family Members After Terror

Introduction: The loss of a loved one in a terror incident is associated with elevated risk for mental health disorders such as prolonged grief disorder (PGD) and posttraumatic stress disorder (PTSD), but the long- term adaptation after such losses are not well understood. This study aims to explore the trajectories of PGD among parents and siblings (n = 129) after the 2011 terror attack on Utøya Island, Norway. Methods: The 19-item Inventory of Complicated grief (ICG) was used to measure PGD at 18, 28, and 40 months post-loss. Latent class growth analysis (LCGA) was used to identify trajectories of grief and a multinomial regression analysis was conducted to examine predictors of class membership. Results: The analysis identified three grief trajectories; moderate/decreasing class (23%), high/slow decreasing class (64%), and a high/chronic class (13%). Predictors of high/slow recovery or chronic grief was female gender, previous depressive symptoms, and intrusion and avoidance symptoms. Conclusion: The findings highlights the difficult grief process and slow recovery that characterizes the majority of close family members bereaved by a terror-incident. Community mental health programs should strive for both early outreach and long-term follow-up after such incidents.

'Sick and tired': Patients reported reasons for not participating in clinical psychiatric research

Background

Meaningful and generalizable research depends on patients' willingness to participate. Studies often fail to reach satisfactory representativeness.

Objective

This paper aims to investigate reasons for not participating in research among young adult patients with psychiatric illness.

Method

A quantitative cross‐sectional study was performed based on questionnaires reported on by 51 psychiatric patients (14 males, 35 females and two unspecified) who had previously declined participation in an ongoing research project. Thereafter, a qualitative interview with subsequent content analysis was conducted with ten additional patients (five males, five females).

Results

The questionnaires indicate being ‘too tired/too sick to participate’ as the most common barrier. Lack of time and fear of needles were other common barriers. Lack of trust or belief in the value of research was less inhibitive. In the interviews, disabling psychiatric symptoms were confirmed as the main reason for not participating. Several potential ways to increase participation were identified, such as simplification of procedures and information as well as providing rewards and feedback, and building relationships before asking.

Conclusion

This study is unusual as it focuses on the group of young people attending psychiatry outpatient clinics we know very little about – those who do not partake in research. Our results indicate that fatigue and sickness reduce research participation and identify factors that may facilitate enrolment of this important group.

Does attrition affect estimates of association: A longitudinal study

Survey research frequently involves missing cases attributable to refusals to participate, lack of success in accessing all potential respondents or loss to follow-up in longitudinal studies. There is concern that those not recruited or those lost are a select group whose absence from a study may bias the findings of the study. This study provides a test of the extent to which selective loss to follow-up in a longitudinal study may lead to biased findings. The Mater-University Study of Pregnancy collected baseline information for 7718 pregnant women. Follow-ups occurred five years, 14 years, 21 years and 27 years after the birth, for 6753 eligible women. Participants at baseline were partitioned according to follow-up status for each follow-up. We compare baseline (at recruitment) measures of association, with these same measures of association for those retained in the study (Group A) and those lost to follow-up (Group B) at each phase of data. Using univariate logistic regression we compared the strength of association between maternal mental health and various baseline socio-demographic factors for different rates of loss to follow-up. Estimates of association at baseline, and at each follow-up are similar irrespective of the rate of loss to follow-up and whether the comparison is with those retained in the study or those lost to follow-up. There were no statistically significant differences in 90.8% of baseline comparisons with Group A, and 96.9% of comparisons with Group B measures of association. We conclude that differential loss to follow-up rarely affects estimates of association. We suggest that loss to follow-up may produce misleading findings only in circumstances where loss to follow-up is combined with a number of other sources of bias.

The long-term physical and psychological health impacts of flooding: A systematic mapping

BACKGROUND

Flooding has caused significant and wide ranging long-term health impacts for affected populations. However, until now, the long-term health outcomes, epidemiological trends and specific impact factors of flooding had not been identified. In this study, the relevant literature was systematically mapped to create the first synthesis of the evidence of the long-term health impacts of flooding.

METHODS

The systematic mapping method was used to collect and categorize all the relevant literature. A study was included if it had a description or measurement of health impacts over six months after flooding. The search was limited to peer reviewed articles and grey literature written in English, published from 1996 to 2016.

RESULTS

A total of 56 critical articles were extracted for the final map, including 5 qualitative and 51 quantitative studies. Most long-term studies investigated the psychological impacts of flooding, including PTSD, depression, anxiety, psychiatric disorders, sleep disorder and suicide. Others investigated the physiological impacts, including health-related quality of life, acute myocardial infarction, chronic diseases, and malnutrition. Social support was proved to be protective factors that can improve health outcomes in the long-term after flooding. To date, there have been relatively few reviews had focused on the long-term health impacts of flooding. This study coded and catalogued the existing evidence across a wide range of variables and described the long-term health consequences within a conceptual map.

DISCUSSION AND CONCLUSIONS

Although there was no boundary between the short-term and the long-term impacts of flooding, the identified health outcomes in this systematic mapping could be used to define long-term health impacts. The studies showed that the prevalence of psychological diseases had a reversed increasing trend occurred even in the long-term in relatively poor post-flooding environments. Further cohort or longitudinal research focused on disability, chronic diseases, relocation population, and social interventions after flooding, are urgently required.

The Effect of Employment Status in Postdisaster Recovery: A Longitudinal Comparative Study Among Employed and Unemployed Affected Residents

Population studies have shown that employed adults are healthier than unemployed adults. In this study, we examined whether this "healthy worker effect" is relevant in postdisaster mental health by examining whether trauma-exposed employed individuals have lower postdisaster initial mental health problems and/or whether they recover faster than trauma-exposed unemployed individuals. We compared the course of postevent intrusion and avoidance reactions, anxiety, depression, and sleeping difficulties of employed residents (n = 291) and unemployed residents (n = 269) affected by a fireworks disaster in a residential area of Enschede, The Netherlands. Measurements took place at 2-3 weeks (T1), 18 months (T2), and 4 years (T3) postdisaster. We used linear mixed-effect models to examine the course of mental health problems. Employment status was relevant, to a degree, in posttrauma recovery; although affected employed residents had significantly lower levels of mental health problems (initially and over time) than the unemployed, ds = 0.41-0.72, the recovery rate was the same for both groups. At T1 (neglecting the DSM 1-month criterion), T2, and T3, the prevalence of probable posttraumatic stress disorder was 45.4%, 18.9%, and 11%, respectively, among employed individuals, and 70.1%, 32.5%, and 30% among unemployed individuals. We concluded that research into the mental health of disaster victims should take employment status into account. Regarding postdisaster care, unemployed individuals may need special attention; although they may recover at the same rate as employed individuals, they suffer from more severe mental health problems, even years after the disaster.

The English national cohort study of flooding and health: cross-sectional analysis of mental health outcomes at year one

Background

In winter 2013/14 there was widespread flooding in England. Previous studies have described an increased prevalence of psychological morbidity six months after flooding. Disruption to essential services may increase morbidity however there have been no studies examining whether those experiencing disruption but not directly flooded are affected.

The National Study of Flooding and Health was established in order to investigate the longer-term impact of flooding and related disruptions on mental health and wellbeing.

Methods

In year one we conducted a cross sectional analysis of people living in neighbourhoods affected by flooding between 1 December 2013 and 31 March 2014. 8761 households were invited to participate. Participants were categorised according to exposure as flooded, disrupted by flooding or unaffected.

We used validated instruments to screen for probable psychological morbidity, the Patient Health Questionnaire (PHQ 2), Generalised Anxiety Disorder scale (GAD-2) and Post Traumatic Stress Disorder (PTSD) checklist (PCL-6).

We calculated prevalence and odds ratios for each outcome by exposure group relative to unaffected participants, adjusting for confounders.

Results

2126 people (23%) responded. The prevalence of psychological morbidity was elevated amongst flooded participants ([n = 622] depression 20.1%, anxiety 28.3%, PTSD 36.2%) and disrupted participants ([n = 1099] depression 9.6%, anxiety 10.7% PTSD 15.2%).

Flooding was associated with higher odds of all outcomes (adjusted odds ratios (aORs), 95% CIs for depression 5.91 (3.91–10.99), anxiety 6.50 (3.77–11.24), PTSD 7.19 (4.33–11.93)).

Flooded participants who reported domestic utilities disruption had higher odds of all outcomes than other flooded participants, (aORs, depression 6.19 (3.30–11.59), anxiety 6.64 (3.84–11.48), PTSD 7.27 (4.39–12.03) aORs without such disruption, depression, 3.14 (1.17–8.39), anxiety 3.45 (1.45–8.22), PTSD 2.90 (1.25–6.73)). Increased floodwater depth was significantly associated with higher odds of each outcome.

Disruption without flooding was associated with borderline higher odds of anxiety (aOR 1.61 (0.94–2.77)) and higher odds of PTSD 2.06 (1.27–3.35)) compared with unaffected participants. Disruption to health/social care and work/education was also associated with higher odds of psychological morbidity.

Conclusions

This study provides an insight into the impact of flooding on mental health, suggesting that the impacts of flooding are large, prolonged and extend beyond just those whose homes are flooded.

Estimating the Prevalence of Ovarian Cancer Symptoms in Women Aged 50 Years or Older: Problems and Possibilities

Diagnostic testing is recommended in women with "ovarian cancer symptoms." However, these symptoms are nonspecific. The ongoing Diagnosing Ovarian Cancer Early (DOVE) Study in Montreal, Quebec, Canada, provides diagnostic testing to women aged 50 years or older with symptoms lasting for more than 2 weeks and less than 1 year. The prevalence of ovarian cancer in DOVE is 10 times that of large screening trials, prompting us to estimate the prevalence of these symptoms in this population. We sent a questionnaire to 3,000 randomly sampled women in 2014-2015. Overall, 833 women responded; 81.5% reported at least 1 symptom, and 59.7% reported at least 1 symptom within the duration window specified in DOVE. We explored whether such high prevalence resulted from low survey response by applying inverse probability weighting to correct the estimates. Older women and those from deprived areas were less likely to respond, but only age was associated with symptom reporting. Prevalence was similar in early and late responders. Inverse probability weighting had a minimal impact on estimates, suggesting little evidence of nonresponse bias. This is the first study investigating symptoms that have proven to identify a subset of women with a high prevalence of ovarian cancer. However, the high frequency of symptoms warrants further refinements before symptom-triggered diagnostic testing can be implemented.

Does exposure type impact differentially over time on the development of mental health disturbances after a technological disaster?

Background

A longitudinal study was conducted in order to assess the impact of the Ghislenghien disaster (July 30th, 2004) on physical, mental and social health in the affected population. The present study explored the risk for the development of four types of mental health disturbances (MHD) due to exposure to different aspects of this technological disaster in comparison with data obtained from previous health surveys among the population of the same province.

Methods

Surveys were conducted 5 months (T1) and 14 months (T2) after the disaster. Potential adult victims (≥15 years) were included (n = 1027 and 579 at T1 and T2 respectively). The “Symptom Checklist-90-Revised” (SCL-90-R) has been used in order to compute actual prevalence rates of somatization-, depression-, anxiety- and sleeping disturbances for three defined exposure categories: direct witnesses who have seen human damage (SHD), direct witnesses who have not seen human damage (NSHD) and indirect witnesses (IW). Those prevalence rates were compared with overall rates using the inhabitants of the province of Hainaut (n = 2308) as reference population. A mental health co-morbidity index was computed. Relative risks were estimated using logistic regression models.

Results

Prevalence rates of the four MHD were much higher for the SHD than for the other exposure groups, at T1 and T2. Moreover, NSHD and IW had no increased risk to develop one of the 4 types of MHD compared to the reference population. The SHD had at T1 and T2 good 5-times a higher risk for somatization, about 4-times for depression and sleeping disorders, and 5- to 6-times for anxiety disorders respectively. Further, they suffered 13 times, respectively 17 times more from all mental disorders together.

Conclusions

The present study calls attention to the fact that mental health problems disturbances are significantly more prevalent and long-lasting among survivors who have directly been exposed to human damage.

Degree of exposure and peritraumatic dissociation as determinants of PTSD symptoms in the aftermath of the Ghislenghien gas explosion

BACKGROUND

This paper investigates risk factors for the development of posttraumatic stress symptoms in the different survivor groups involved in a technological disaster in Ghislenghien (Belgium). A gas explosion instantly killed five firefighters, one police officer and 18 other people. Moreover, 132 people were wounded among which many suffered severe burn injuries.

METHODS

In the framework of a large health survey of people potentially involved in the disaster, data were collected from 3,448 households, of which 7,148 persons aged 15 years and older, at 5 months (T1) and at 14 months (T2) after the explosion. Hierarchical regression was used to determine the significant predictors and to assess their proportion in variance accounted for.

RESULTS

The degree of exposure to the disaster was a predictor of the severity of posttraumatic stress symptoms. Peritraumatic dissociation appeared to be the most important predictor of the development of posttraumatic stress symptoms at T1. But at T2, posttraumatic stress symptoms at T1 had become the most important predictor. Dissatisfaction with social support was positively linked to development of posttraumatic stress symptoms at T1 and to the maintenance of these symptoms at T2. Survivors who received psychological help reported significant benefits.

CONCLUSIONS

In harmony with the findings from studies on technological disasters, at T1 6,0% of the respondents showed sufficient symptoms to meet all criteria for a full PTSD. At T2, 6,6% still suffered from posttraumatic stress symptoms. The symptoms of the different victim categories clearly indicated the influence of the degree of exposure on the development of posttraumatic stress symptoms. Problems inherent to retrospective scientific research after a disaster are discussed.

Evaluation of non-response bias in a cohort study of World Trade Center terrorist attack survivors

Background

Few longitudinal studies of disaster cohorts have assessed both non-response bias in prevalence estimates of health outcomes and in the estimates of associations between health outcomes and disaster exposures. We examined the factors associated with non-response and the possible non-response bias in prevalence estimates and association estimates in a longitudinal study of World Trade Center (WTC) terrorist attack survivors.

Methods

In 2003–04, 71,434 enrollees completed the WTC Health Registry wave 1 health survey. This study is limited to 67,670 adults who were eligible for both wave 2 and wave 3 surveys in 2006–07 and 2011–12. We first compared the characteristics between wave 3 participants (wave 3 drop-ins and three-wave participants) and non-participants (wave 3 drop-outs and wave 1 only participants). We then examined potential non-response bias in prevalence estimates and in exposure-outcome association estimates by comparing one-time non-participants (wave 3 drop-ins and drop-outs) at the two follow-up surveys with three-wave participants.

Results

Compared to wave 3 participants, non-participants were younger, more likely to be male, non-White, non-self enrolled, non-rescue or recovery worker, have lower household income, and less than post-graduate education. Enrollees’ wave 1 health status had little association with their wave 3 participation. None of the disaster exposure measures measured at wave 1 was associated with wave 3 non-participation. Wave 3 drop-outs and drop-ins (those who participated in only one of the two follow-up surveys) reported somewhat poorer health outcomes than the three-wave participants. For example, compared to three-wave participants, wave 3 drop-outs had a 1.4 times higher odds of reporting poor or fair health at wave 2 (95% CI 1.3-1.4). However, the associations between disaster exposures and health outcomes were not different significantly among wave 3 drop-outs/drop-ins as compared to three-wave participants.

Conclusion

Our results show that, despite a downward bias in prevalence estimates of health outcomes, attrition from the WTC Health Registry follow-up studies does not lead to serious bias in associations between 9/11 disaster exposures and key health outcomes. These findings provide insight into the impact of non-response on associations between disaster exposures and health outcomes reported in longitudinal studies.

Social organizational stressors and post-disaster mental health disturbances: a longitudinal study

Social organizational stressors are well-known predictors of mental health disturbances (MHD). However, to what extent these stressors predict post-disaster MHD among employed victims hardly received scientific attention and is clearly understudied. For this purpose we examined to what extent these stressors independently predict MHD 1.5 years post-disaster over and above well-known risk factors such as disaster exposure, initial MHD and lack of general social support, life-events in the past 12 months and demographics (N=423). Exposure, social organizational stressors and support were significantly associated with almost all examined mental health disturbances on a bi-variate level. Multivariate logistic regression analyses showed that these stressors, i.e. problems with colleagues, independently predicted anxiety (Adj. OR=5.93), depression (Adj. OR=4.21), hostility (Adj. OR=2.85) and having two or more mental health disturbances (Adj. OR=3.39) in contrast to disaster exposure. Disaster exposure independently predicted symptoms of PTSD symptoms (Adj. OR=2.47) and agoraphobia (Adj. OR=2.15) in contrast to social organizational stressors. Importantly, levels of disaster exposure were not associated nor correlated with (levels of) social organizational stressors. Findings suggest that post-disaster mental health care programs aimed at employed affected residents, should target social organizational stressors besides disaster-related stressors and lack of general social support.

The associations between coping self-efficacy and posttraumatic stress symptoms 10 years postdisaster: differences between men and women

The mediating role of coping self-efficacy (CSE) perceptions between disaster-related posttraumatic stress symptoms (PSS) in the intermediate term (4 years postevent) and PSS in the long term (10 years postevent) were examined. Participants were 514 adult Dutch native residents affected by the Enschede fireworks disaster. The disaster (May, 2000) was caused by a massive explosion in a fireworks storage facility that destroyed a residential area. Multiple regression analysis and path analysis were used to examine the mediating role of CSE and whether the mediating role was the same for men and women. Age, education, disaster exposure, home destruction, optimism, and stressful life events were also taken into account. Regression analysis showed that the former variables were not associated with PSS at 10 years postevent, in contrast to PSS at 4 years, and were therefore omitted from the path analyses. CSE assessed at 10 years postdisaster partially mediated the relationship between PSS at 4 and PSS at 10 years postdisaster. Post hoc multigroup analysis showed that this effect was significantly stronger for men, whereas the association between PSS at 4 and 10 years postevent was stronger for women. PSS at 10 years postevent were better predicted among men (explained variance 59.5% vs 50.8%).

Persistent mental health disturbances during the 10 years after a disaster: four-wave longitudinal comparative study

AIM

Although some studies have examined the long-term effects of disasters, very little is known about severe persistent symptoms following disasters. The aim of the present study was to examine persistent mental health problems and to what extent disaster exposure predicts long-term persistent disturbances.

METHODS

Following a major disaster, a four-wave study was conducted (surveys 2-3 weeks, 18 months, 4 years and 10 years after the event) that examined severe post-traumatic stress disorder (PTSD) symptomatology (Impact of Event Scale), anxiety and depression symptoms and sleeping problems (Symptom Check List-90-R), and use of physician-prescribed tranquilizers. Participants were affected adult Dutch native residents (n = 1083). At wave 2 and 3, a control group participated (n = 694). At wave 1, severity of disaster exposure was examined. Multiple imputation was used to target the problem of missing data across surveys due to non-response such as in the fourth wave (61%).

RESULTS

In total, 6.7% (95% confidence interval [CI]: 5.1-8.2) developed persistent PTSD symptoms during the 10 years after the event. For anxiety, depression, sleeping problems these prevalences were 3.8% (95%CI: 2.7-5.0), 6.2% (95%CI: 4.7-7.6) and 4.8% (95%CI: 3.5-6.1) respectively. In total 1.3% (95%CI: 0.6-2.0) used tranquilizers at all waves. Approximately one out of 10 with severe symptoms 2-3 weeks after the event, developed persistent symptoms. Even in the long term, affected residents compared to controls had more often chronic anxiety symptoms and sleeping problems. High disaster exposure independently predicted persistent PTSD symptoms (adjusted odds ratio [adj. OR], 4.20; 95%CI: 2.02-8.74, P < 0.001), anxiety (adj. OR, 3.43; 95%CI: 1.28-9.20, P < 0.01), depression symptoms (adj. OR, 2.95; 95%CI: 1.26-6.93, P < 0.01), and sleeping problems (adj. OR, 3.74; 95%CI: 1.56-8.95, P < 0.001).

CONCLUSION

Post-disaster mental health care should (also) target persistent mental health disturbances in the long term, especially PTSD, anxiety, depression symptoms, and sleeping problems. High disaster exposure may be an early marker for risk of persistent symptoms.

Disaster exposure as a risk factor for mental health problems, eighteen months, four and ten years post-disaster--a longitudinal study

BACKGROUND

Disaster experiences have been associated with higher prevalence rates of (mental) health problems. The objective of this study was to examine the independent relation between a series of single disaster experiences versus the independent predictive value of a accumulation of disaster experiences, i.e. a sum score of experiences and symptoms of distress and post-traumatic stress disorder (PTSD).

METHODS

Survivors of a fireworks disaster participated in a longitudinal study and completed a questionnaire three weeks (wave 1), eighteen months (wave 2) and four years post-disaster (wave 3). Ten years post-disaster (wave 4) the respondents consisted of native Dutch survivors only. Main outcome measures were general distress and symptoms of PTSD.

RESULTS

Degree of disaster exposure (sum score) and some disaster-related experiences (such as house destroyed, injured, confusion) were related to distress at waves 2 and 3. This relation was mediated by distress at an earlier point in time. None of the individual disaster-related experiences was independently related to symptoms of distress. The association between the degree of disaster exposure and symptoms of PTSD at waves 2 and 3 was still statistically significant after controlling for symptoms of distress and PTSD at earlier point in time. The variable 'house destroyed' was the only factor that was independently related to symptoms of PTSD at wave 2. Ten years after the disaster, disaster exposure was mediated by symptoms of PTSD at waves 2 and 3. Disaster exposure was not independently related to symptoms of PTSD ten years post-disaster.

CONCLUSIONS

Until 4 years after the disaster, degree of exposure (a sum score) was a risk factor for PTSD symptoms while none of the individual disaster experiences could be identified as an independent risk factor. Ten years post-disaster, disaster exposure was no longer an independent risk factor for symptoms of PTSD. Since symptoms of PTSD and distress at earlier waves perpetuate the symptoms at later waves, health care workers should aim their resources at those who still have symptoms after one and a half year post-disaster, to prevent health problems at medium and long-term.

Epidemiologic methods lessons learned from environmental public health disasters: Chernobyl, the World Trade Center, Bhopal, and Graniteville, South Carolina

BACKGROUND

Environmental public health disasters involving hazardous contaminants may have devastating effects. While much is known about their immediate devastation, far less is known about long-term impacts of these disasters. Extensive latent and chronic long-term public health effects may occur. Careful evaluation of contaminant exposures and long-term health outcomes within the constraints imposed by limited financial resources is essential.

METHODS

Here, we review epidemiologic methods lessons learned from conducting long-term evaluations of four environmental public health disasters involving hazardous contaminants at Chernobyl, the World Trade Center, Bhopal, and Graniteville (South Carolina, USA).

FINDINGS

We found several lessons learned which have direct implications for the on-going disaster recovery work following the Fukushima radiation disaster or for future disasters.

INTERPRETATION

These lessons should prove useful in understanding and mitigating latent health effects that may result from the nuclear reactor accident in Japan or future environmental public health disasters.

Stress sensitization following a disaster: a prospective study

BACKGROUND

According to the stress sensitization hypothesis, prior exposure to extreme stressors may lead to increased responsiveness to subsequent stressors. It is unclear whether disaster exposure is associated with stress sensitization and, if so, whether this effect is lasting or temporary. This study aimed to investigate the occurrence and duration of stress sensitization prospectively following a major disaster.

METHOD

Residents affected by a fireworks disaster (n=1083) participated in surveys 2-3 weeks (T1), 18-20 months (T2) and almost 4 years (T3) after the disaster. Participants reported disaster exposure, including direct exposure, injury and damage to their home at T1, and also stressful life events (SLEs) at T2 and T3. Feelings of anxiety and depression, concentration difficulty, hostility, sleep disturbance, and intrusion and avoidance of disaster-related memories were used as indicators of distress.

RESULTS

Residents whose home was completely destroyed responded with greater distress to SLEs reported 18-20 months following the disaster than residents whose home was less damaged. There were no differences in stress responsiveness almost 4 years after the disaster.

CONCLUSIONS

During the first years after a disaster, stress sensitization may occur in disaster survivors who experienced extreme disaster exposure. Stress sensitization may explain the persistence or progression of distress over time following extreme stressor exposure.

Impact of physical injury on mental health after the 2004 Southeast Asia tsunami

BACKGROUND

The risk of developing enduring post-traumatic stress reactions and mental health problems in the aftermath of disasters is substantial. However, there are inconsistencies regarding the contribution of physical injury as an independent risk factor for developing psychiatric morbidity after disasters.

AIMS

The aim was to assess whether physical injury was associated with post-traumatic stress reactions and general mental health after adjusting for perceived life-threat in the aftermath of the 2004 tsunami.

METHODS

A sample of 1501 highly exposed survivors from the 2004 Southeast Asia tsunami was selected from a cohort of Swedish survivors surveyed 14 and 36 months after the event. The impact of physical injury on post-traumatic stress and general mental health was assessed by regression models accounting for subjective life-threat.

RESULTS

Physical injury was associated with higher levels of post-traumatic stress reactions and poorer general mental health. These associations were observed at both 14 and 36 months after the disaster.

CONCLUSIONS

Physical injury has a specific contribution to the association between traumatic experience and both post-traumatic stress reactions and general mental health in victims of the 2004 tsunami. The effect is stable over several years.

Acculturation and post-disaster mental health problems among affected and non-affected immigrants: a comparative study

BACKGROUND

It is unknown to what extent acculturation among disaster-affected immigrants is associated with mental health problems (MHP) compared to non-affected immigrants.

METHODS

We examined the associations between acculturation and post-disaster MHP among affected and non-affected immigrants in The Netherlands.

RESULTS

Among the affected group, keeping norms and values of original culture and limited skills to cope with the demands of the new society were independently associated with PTSD-symptomatology, anxiety, depression, hostility, and somatic problems at 18 months post-event. In the non-affected comparison group no associations were found. Interestingly, levels of acculturation did not differ between both groups, in contrast to MHP.

LIMITATIONS

The acculturation levels could be influenced by the experience of a disaster. However, levels did not differ statistically between the study groups. Furthermore, the groups were reasonably small and the response rates were, although not uncommon in health studies among immigrants, relatively low.

CONCLUSIONS

The findings of this unique study clearly suggest that post-disaster mental health policies should target low levels of skills to survive in the new society. Furthermore, the acculturation domain of keeping traditional norms and values can be contrary to the Dutch care after a disaster where self-efficacy and individualistic, cognitive functioning are the central goals. Further research is warranted to explore and examine post-event interventions aimed at increasing the levels of acculturation that may facilitate recovery.

Symptom attribution and presentation in general practice after an extreme life event

BACKGROUND

A serious life event is likely to shape attributions relating to symptoms experienced afterwards. While they may play an important role in prognosis and seeking care, such perceptions have hardly been studied among survivors of a disaster.

OBJECTIVE

To investigate the association between self-reported health problems that have been attributed to an extreme life event and the symptoms presented to GPs.

METHODS

A two-wave longitudinal survey (2-3 weeks and 18 months) among survivors of a fireworks disaster was combined with a continuous morbidity surveillance in general practice. Symptoms attributed to the disaster reported in an open-ended question in the two waves were analysed using descriptive statistics. Differences in presented symptoms over time were analysed using logistic multilevel analysis.

RESULTS

More than half of the respondents reported health problems, which were, in their opinion, related to the disaster. Psychological problems were most frequently reported in association with the disaster, and in contrast to physical attributed symptoms, presentation of these problems in general practice decreased over time. In the total sample, musculoskeletal symptoms were less frequently presented in the longer term. Survivors who attributed symptoms to the disaster at both waves or after 18 months only most often presented such symptoms to the GP.

CONCLUSION

Survivors attributed psychological problems and physical symptoms to the disaster at short-term and midterm post-disaster. Most of these survivors presented such symptoms to the GP. Attribution of symptoms to an extreme life event such as a disaster may therefore require special attention from the GP.

Lack of perceived social support among immigrants after a disaster: comparative study

BACKGROUND

Disaster research suggests that immigrant groups who are affected by a disaster receive less emotional support than their native counterparts. However, it is unclear to what extent these differences can be attributed to post-disaster mental health problems or whether they were present before the event.

AIMS

To examine the association between lack of social support, immigration status and victim status, as well as differences in support between immigrants and Dutch natives with disaster-related post-traumatic stress disorder (PTSD).

METHOD

Social support and psychological distress were assessed among immigrants and Dutch natives, among affected and non-affected individuals 4 years post disaster. Post-traumatic stress disorder was examined in the affected groups.

RESULTS

Affected immigrants more often lacked various kinds of perceived social support compared with affected Dutch natives. Remarkably, we found no differences in support between affected immigrants and non-affected immigrants. Immigrants with PTSD differ on only two out of six aspects of support from the Dutch natives with PTSD.

CONCLUSIONS

Results clearly indicate that differences in support between immigrants and Dutch natives are not so much a consequence of the disaster but were largely present before the disaster.

The psychological impact of exposure to floods

A number of studies have shown a range of symptoms resulting from exposure to natural disasters such as flooding. Among these consequences, individuals may experience symptoms of post-traumatic stress disorder (PTSD), depression and anxiety. The aim of this study was to examine the psychological impact of flooding in the UK. A cross-sectional survey was used to investigate the psychological symptoms associated with the aftermath of the flood amongst adults living in the affected communities. A questionnaire battery including the Harvard Trauma Questionnaire (trauma and symptoms associated with PTSD), Hopkins Symptom Checklist (anxiety and depression), Coping Strategies Questionnaire and a range of questions addressing sociodemographic characteristics and factors relating to the flood was administered to households in flood-affected areas. Four hundred and forty four completed questionnaires were returned. 27.9% of participants met criteria for symptoms associated with PTSD, 24.5% for anxiety and 35.1% for depression. Females had higher mean scores on PTSD, anxiety and depression than males. Most frequently reported coping strategies were rational, detached and avoidant, with the least frequent being emotional coping. Having to vacate home following flood, previous experience of flooding and poor health were associated with greater psychological distress. Detached coping appeared to be related to less distress. Although it is not possible to determine whether the symptoms were a direct consequence of the flood, symptoms of distress are a significant issue amongst communities affected by environmental events warranting further attention to prevent chronic distress.

Psychological distress and sick leave in Swedish survivors of the 2004 tsunami: a comparison with a population sample

Disaster studies of the effects of trauma exposure on subsequent psychological health have seldom used population comparisons. A total of 1463 tsunami survivors from Stockholm were categorized according to type of exposure, and compared on measures of General Health Questionnaire and sick leave, with a matched population-based sample of 12,045 individuals from the same region. Data from the survivor group were obtained through a postal questionnaire 14 months postdisaster. Data from the population sample were collected in the same year. In comparison to the population sample, levels of sick leave ranged from higher in multiply exposed groups to lower in the least exposed group. For psychological distress, levels in multiply and moderately exposed groups were higher, and in lower exposed groups comparable. The use of a population comparison resulted in a support of recent research showing a relative resiliency of survivors exposed during disaster to potential trauma of lesser severity.

A longitudinal study on the Ghislenghien disaster in Belgium: strengths and weaknesses of the study design and influence on response rate

Background

A longitudinal study was conducted in order to assess the impact of the Ghislenghien disaster (Belgium) on physical, mental and social health, and to evaluate the prevalence of Post-Traumatic Stress Disorder (PTSD) in the affected population.

Objectives

To describe the set up of the study, to report on the strengths and weaknesses of the methodology employed and its influence on response rate. To clarify the importance of the study for the management of disasters.

Methods/Design

The study included adults (≥ 15 years) and children (8-14 years) at risk of developing adverse health effects related to the disaster. Subjects were connected to the disaster through their geographical or professional proximity as well as connections through relatives. Questionnaires were sent by regular mail 5 months and 14 months after the disaster. Pearson Chi square tests were used to investigate whether the response rate at 14 months depended on the exposure classification.

Results

The response rate at household level was respectively 18% (n = 607 families) and 56% (n = 338 families) 5 months and 14 months after the disaster. Response rate at the follow up period did not significantly differ by exposure classification.

Discussion

This paper discusses the difficulties and challenges encountered during the design of the study. It discusses the determinants of response in relation to disaster related characteristics. It further provides an overview of lessons learnt and the significance of the study for the management of large scale emergencies.

Mental health of workers in Toulouse 2 years after the industrial AZF disaster: first results of a longitudinal follow-up of 3,000 people

INTRODUCTION

On September 21, 2001, the AZF petrochemical factory near Toulouse (France) exploded. A cross-sectional survey of Toulouse workers took place in 2002 and then, a cohort follow-up began in 2003. The aim of this paper is to study the associations between various factors describing exposure to the disaster, and anxiety and depressive symptoms, assessed at cohort inclusion 2 years afterwards.

METHODS

In 2003, 3,006 people were included in the cohort. Psychological distress was measured by the GHQ28 at inclusion. Factors related to exposure to the disaster, such as personal distance from the site, physical injury, immediate psychological symptoms, and material and social effects, came from the 2002 cross-sectional survey. The links between mental health symptoms and exposure were studied in multivariate analyses by logistic regression.

RESULTS

The prevalence of psychological distress was 47% at inclusion in the cohort. It varied according to sex and occupational class: blue-collar workers and self-employed people were most highly affected. Factors such as a history of depression, injury to a close friend or family member, sick-leaves and immediate psychological symptoms were associated with psychological distress 2 years later. These associations differed according to sex.

CONCLUSION

This study shows links between the industrial disaster and psychological distress 2 years afterwards. The results about risk factors differ according to sex, and identify particularly vulnerable populations. It should guide preventive interventions in such situation.

Nonresponse to a population-based postdisaster postal questionnaire study

We examined nonparticipation in a 2-year postdisaster mail survey of Norwegian tourists evacuated from countries affected by the 2004 tsunami. One hundred seventy-one persons out of a random sample of 330 nonparticipants were telephone interviewed concerning disaster exposure, current posttraumatic stress reactions, and reasons for not participating. Fewer nonparticipants than participants had been in a place directly affected by the tsunami. Nonparticipants reported less perceived threat of death and lower levels of posttraumatic stress reactions. Reasons for not participating were "lack of interest or time" (39.2%), "lack of relevant experiences" (32.2%), and "too personal or emotionally disturbing" (15.2%). Our findings suggest that postdisaster studies may be biased in the direction of more severe disaster exposure and pronounced posttraumatic stress reactions.

Risk factors for unexplained symptoms after a disaster: a five-year longitudinal study in general practice

BACKGROUND

Medically unexplained symptoms (MUS) are a common reason to seek medical care. When presented to the general practitioner (GP), more than three-quarters of symptoms such as stomach ache, headache, and pain in bones and muscles cannot be explained by a medical disorder.

OBJECTIVE

The authors examined the course of MUS presented to the GP in the 1 year before the disaster and in the 4 years after a disaster in order to study the risk factors for MUS.

METHOD

Data were extracted from the electronic medical records of survivors and from a questionnaire (N=1,216).

RESULTS

Although the mean number of MUS was significantly increased statistically in the first 2 years post-disaster, the increase was not clinically significant.

CONCLUSION

The authors identified several important risk factors, such as immigrant status and psychological problems, that are easy for GPs to recognize. Despite this, the sensitivity of the regression model was relatively low.

Use of multiple imputation in the epidemiologic literature

The authors attempted to catalog the use of procedures to impute missing data in the epidemiologic literature and to determine the degree to which imputed results differed in practice from unimputed results. The full text of articles published in 2005 and 2006 in four leading epidemiologic journals was searched for the text imput. Sixteen articles utilizing multiple imputation, inverse probability weighting, or the expectation-maximization algorithm to impute missing data were found. The small number of relevant manuscripts and diversity of detail provided precluded systematic analysis of the use of imputation procedures. To form a bridge between current and future practice, the authors suggest details that should be included in articles that utilize these procedures.

Risk factors for physical symptoms after a disaster: a longitudinal study

BACKGROUND

Although symptoms such as fatigue, headache and pain in bones and muscles are common after disasters, risk factors for these symptoms among disaster survivors have rarely been studied. We examined predisposing, precipitating and perpetuating factors for these physical symptoms among survivors of a man-made disaster. In addition, we examined whether risk factors for physical symptoms differ between survivors and controls.

METHOD

Survivors completed a questionnaire 3 weeks (n=1567), 18 months and 4 years after the disaster. Symptoms and risk factors were measured using validated questionnaires. A comparison group was included at waves 2 and 3 (n=821). Random coefficient analysis (RCA) was used to study risk factors for symptoms.

RESULTS

Female gender [beta (beta)=1.0, 95% confidence interval (CI) 0.6-1.4], immigrant status (beta=1.0, 95% CI 0.6-1.4) and pre-disaster psychological problems (beta=0.8, 95% CI 0.1-1.4) were predisposing factors for symptoms. Although disaster-related factors were predictors, the relationship between symptoms and disaster-related factors was not very strong and the magnitude of this association was reduced when perpetuating factors were added. Intrusions and avoidance, depression, anxiety and sleeping problems were important perpetuating factors for physical symptoms among survivors and mediated the association between traumatic stress and physical symptoms. Risk factors for symptoms were comparable between survivors and controls.

CONCLUSIONS

The results indicate that health-care workers should be alert for physical symptoms among female survivors, immigrant survivors and individuals with a high level of psychological problems both before and after a disaster.

Correlates of mental health services utilization 18 months and almost 4 years postdisaster among adults with mental health problems

The authors assess the correlates of mental health services utilization (MHS) after a disaster among adults with mental health problems. Data of a three-wave longitudinal study among adult survivors of a fireworks disaster (T1: 2-3 weeks, T2: 18 months, T3: almost 4 years postdisaster) were linked with their electronic medical records (N = 649). Multivariate logistic regression analyses showed that triple comorbidity of PTSD and high levels of anxiety and depression symptoms were positively associated with self-reported MHS utilization at T2 (n = 270) and T3 (n = 216). Private insurance, predisaster psychological problems, and relocation were associated with MHS utilization at T2 while female gender, being single, and migrant status was associated with MHS utilization at T3. Receiving treatment at T2 was positively associated with receiving treatment at T3, as opposed to medium optimism at T2.

Are physical symptoms among survivors of a disaster presented to the general practitioner? A comparison between self-reports and GP data

Background

Most studies examining medically unexplained symptoms (MUS) have been performed in primary or secondary care and have examined symptoms for which patients sought medical attention. Disasters are often described as precipitating factors for MUS. However, health consequences of disasters are typically measured by means of questionnaires, and it is not known whether these self-reported physical symptoms are presented to the GP. It is also not known if the self-reported symptoms are related to a medical disorder or if they remain medically unexplained. In the present study, three research questions were addressed. Firstly, were self-reported symptoms among survivors presented to the GP? Secondly, were the symptoms presented to the GP associated with a high level of functional impairment and distress? Thirdly, what was the GP's clinical judgment of the presented symptoms, i.e. were the symptoms related to a medical diagnosis or could they be labeled MUS?

Methods

Survivors of a man-made disaster (N = 887) completed a questionnaire 3 weeks (T1) and 18 months (T2) post-disaster. This longitudinal health survey was combined with an ongoing surveillance program of health problems registered by GPs.

Results

The majority of self-reported symptoms was not presented to the GP and survivors were most likely to present persistent symptoms to the GP. For example, survivors with stomachache at both T1 and T2 were more likely to report stomachache to their GP (28%) than survivors with stomachache at only T1 (6%) or only T2 (13%). Presentation of individual symptoms to the GP was not consistently associated with functional impairment and distress. 56 – 91% of symptoms were labeled as MUS after clinical examination.

Conclusion

These results indicate that the majority of self-reported symptoms among survivors of a disaster are not presented to the GP and that the decision to consult with a GP for an individual symptom is not dependent on the level of impairment and distress. Also, self-reported physical symptoms such as headache, back pain and shortness of breath are likely to remain medically unexplained after the clinical judgment of a GP.

The association between dispositional optimism and mental health problems among disaster victims and a comparison group: a prospective study

BACKGROUND

It is unclear whether the associations between the level of dispositional optimism on the one hand, and depression symptoms and other health problems on the other hand among disaster victims differ from the associations among non-affected residents.

METHODS

To assess the associations between the level of dispositional optimism and health problems among disaster victims and non-affected residents, data of the longitudinal Enschede Fireworks Disaster Study was analyzed. Participants in the present study consisted of adult native Dutch victims of the disaster (N=662) and a non-affected comparison group (N=526). Both groups participated 18 months (T1) and almost four years post-disaster (T2). Multivariate logistic regression analyses were applied to examine the association between optimism and health problems among both groups.

RESULTS

Results showed that pessimistic victims were more at risk for severe depression symptoms and obsessive-compulsive symptoms than optimistic victims when controlling for demographic characteristics, life events, smoking, and existing health problems at T1. However, pessimistic participants in the comparison group were also more at risk for severe anxiety symptoms, sleeping problems, somatic problems, and problems in social functioning than optimistic control participants.

LIMITATIONS

We had no information on dispositional optimism before 18 months post-disaster.

CONCLUSIONS

Pessimists at baseline are more at risk for health problems after 27 months than optimists. However, among non-affected residents pessimism is a stronger independent risk factor than among victims. Results suggest that professional helpers such as general practitioners, psychologists and psychiatrists should not rely too much on optimistic views of disaster victims.

Use of mental health services among disaster survivors: predisposing factors

Background

Given the high prevalence of mental health problems after disasters it is important to study health services utilization. This study examines predictors for mental health services (MHS) utilization among survivors of a man-made disaster in the Netherlands (May 2000).

Methods

Electronic records of survivors (n = 339; over 18 years and older) registered in a mental health service (MHS) were linked with general practice based electronic medical records (EMRs) of survivors and data obtained in surveys. EMR data were available from 16 months pre-disaster until 3 years post-disaster. Symptoms and diagnoses in the EMRs were coded according to the International Classification of Primary Care (ICPC). Surveys were carried out 2–3 weeks and 18 months post-disaster, and included validated questionnaires on psychological distress, post-traumatic stress reactions and social functioning. Demographic and disaster-related variables were available. Predisposing factors for MHS utilization 0–18 months and 18–36 months post-disaster were examined using multiple logistic regression models.

Results

In multiple logistic models, adjusting for demographic and disaster related variables, MHS utilization was predicted by demographic variables (young age, immigrant, public health insurance, unemployment), disaster-related exposure (relocation and injuries), self-reported psychological problems and pre- and post-disaster physician diagnosed health problems (chronic diseases, musculoskeletal problems). After controlling for all health variables, disaster intrusions and avoidance reactions (OR:2.86; CI:1.48–5.53), hostility (OR:2.04; CI:1.28–3.25), pre-disaster chronic diseases (OR:1.82; CI:1.25–2.65), injuries as a result of the disaster (OR:1.80;CI:1.13–2.86), social functioning problems (OR:1.61;CI:1.05–2.44) and younger age (OR:0.98;CI:0.96–0.99) predicted MHS utilization within 18 months post-disaster. Furthermore, disaster intrusions and avoidance reactions (OR:2.29;CI:1.04–5.07) and hostility (OR:3.77;CI:1.51–9.40) predicted MHS utilization following 18 months post-disaster.

Conclusion

This study showed that several demographic and disaster-related variables and self-reported and physician diagnosed health problems predicted post-disaster MHS-use. The most important factors to predict post-disaster MHS utilization were disaster intrusions and avoidance reactions and symptoms of hostility (which can be identified as symptoms of PTSD) and pre-disaster chronic diseases.

A longitudinal comparative study of the physical and mental health problems of affected residents of the firework disaster Enschede, The Netherlands

OBJECTIVES

After the firework disaster in Enschede, The Netherlands, on 13 May 2000, a longitudinal health study was carried out. Study questions were: (1) did the health status change over this period; and (2) how is the health status 18 months after the disaster compared with controls?

STUDY DESIGN

A longitudinal comparative study with two surveys at 3 weeks and 18 months after the disaster.

METHODS

A control group for the affected residents was included in the second survey. Respondents filled in a set of validated questionnaires measuring their physical and mental health problems.

RESULTS

The prevalence of physical and emotional role limitations, severe sleeping problems, feelings of depression and anxiety, as well as intrusion and avoidance decreased from 3 weeks to 18 months after the disaster for the affected residents. Independent of background characteristics and other life events, residents had 1.5 to three times more health problems than the control group; for example, physical role limitations (odds ratio [OR]=1.5, 95% confidence interval [CI] 1.2-2.0) and anxiety (OR=3.1, 95% CI 2.4-4.2).

CONCLUSIONS

Although health problems decreased compared with 3 weeks after the disaster, 18 months after the disaster, the affected residents had more health problems than the people from the control group.

Selective attrition and bias in a longitudinal health survey among survivors of a disaster

Background

Little is known about the response mechanisms among survivors of disasters. We studied the selective attrition and possible bias in a longitudinal study among survivors of a fireworks disaster.

Methods

Survivors completed a questionnaire three weeks (wave 1), 18 months (wave 2) and four years post-disaster (wave 3). Demographic characteristics, disaster-related factors and health problems at wave 1 were compared between respondents and non-respondents at the follow-up surveys. Possible bias as a result of selective response was examined by comparing prevalence estimates resulting from multiple imputation and from complete case analysis. Analysis were stratified according to ethnic background (native Dutch and immigrant survivors).

Results

Among both native Dutch and immigrant survivors, female survivors and survivors in the age categories 25–44 and 45–64 years old were more likely to respond to the follow-up surveys. In general, disasters exposure did not differ between respondents and non-respondents at follow-up. Response at follow-up differed between native Dutch and non-western immigrant survivors. For example, native Dutch who responded only to wave 1 reported more depressive feelings at wave 1 (59.7%; 95% CI 51.2–68.2) than Dutch survivors who responded to all three waves (45.4%; 95% CI 41.6–49.2, p < 0.05). Immigrants who responded only to wave 1 had fewer health problems three weeks post-disaster such as depressive feelings (M = 69.3%; 95% CI 60.9–77.6) and intrusions and avoidance reactions (82.7%; 95% CI 75.8–89.5) than immigrants who responded to all three waves (respectively 89.9%; 95% CI 83.4–96.9 and 96.3%; 95% CI 92.3–100, p < .01). Among Dutch survivors, the imputed prevalence estimates of wave 3 health problems tended to be higher than the complete case estimates. The imputed prevalence estimates of wave 3 health problems among immigrants were either unaffected or somewhat lower than the complete case estimates.

Conclusion

Our results indicate that despite selective response, the complete case prevalence estimates were only somewhat biased. Future studies, both among survivors of disasters and among the general population, should not only examine selective response, but should also investigate whether selective response has biased the complete case prevalence estimates of health problems by using statistical techniques such as multiple imputation.

Health-related quality of life and mental health problems after a disaster: are chronically ill survivors more vulnerable to health problems?

Studies have shown that the chronically ill are at higher risk for reduced health-related quality of life (HRQL) and for mental health problems. A combination with traumatic events might increase this risk. This longitudinal study among 1216 survivors of a disaster examines whether chronically ill survivors had a different course of HRQL and mental health problems compared to survivors without chronic diseases. HRQL and mental health problems were measured 3 weeks, 18 months and 4 years post-disaster. Data on pre-disaster chronic diseases was obtained from the electronic medical records of general practitioners. Random coefficient analyses showed significant interaction effects for social functioning, bodily pain and emotional role limitations at T2 only. Chronically ill survivors did not consistently have a different course of general health, physical role limitations, and mental health problems. In conclusion, chronic diseases were not an important risk factor for impaired HRQL and mental health problems among survivors.