Background/Rationale
Flooding is the most common type of disaster, with more than 2 billion people affected worldwide between 1998 and 2017. 1 Between 2020-2022, 60 weather and climate disasters affected the US, with losses exceeding $1 billion (USD) each. 2 Approximately 3% of the US population lives in areas subject to 1% annual chance coastal flood hazard.Reference Crowell, Coulton and Johnson 3 Projections for the Atlantic and eastern North Pacific Oceans include increased hurricane rainfall and intensity.Reference Reidmiller, Avery and Easterling 4 As climate change increases, the number of people impacted by climate-related hazards grows. 5
Extreme weather and climate-related events can have lasting mental health consequences, especially if these events cause loss of income and resources or community relocation.Reference Reidmiller, Avery and Easterling 4 Hazard-related events range from property loss to displacement from home and community. In a sample of 810 persons exposed to Hurricane Katrina, the prevalence of post-traumatic stress disorder (PTSD) in the 2 years following the hurricane was 22.5%, while predictors of PTSD included hurricane-related financial loss, post-disaster stressors, and post-disaster traumatic events.Reference Galea, Tracy and Norris 6
However, there is a lack of epidemiological evidence on the mental health impact of hurricanes and flooding. Many research findings have relied on cross-sectional data or studies lacking a pre-disaster assessment or appropriate control group. This methodological limitation may result in biased findings. An understanding of the literature assessing the mental health impact of natural hazards has become increasingly important and relevant for disaster response planning.
Previous systematic reviews of mental health outcomes after disasters have assessed a variety of natural hazards, including earthquakes,Reference Cénat, McIntee and Blais-Rochette 7 , Reference Rezayat, Sahebdel and Jafari 8 flooding,Reference Fernandez, Black and Jones 9 and exposure to any type of disasterReference Palinkas and Wong 11 , Reference Neria, Nandi and Galea 10 ‒Reference Beaglehole, Mulder and Frampton 14 The present review focuses exclusively on studies concerning exposure to hurricane and/or flooding. Other types of natural and human-induced disasters—such as terrorism, train derailments, and earthquakes—lack time for preparation and evacuation common before a hurricane or flood. The preparation and evacuation stage may influence the risk of mental health outcomes in survivors in a unique way as people with more resources may mitigate negative outcomes by evacuatingReference Galea, Tracy and Norris 6—an option not available to those who are exposed to sudden-onset hazards such as earthquakes or tornadoes. Prior research has shown a differential impact on communities affected by hurricanes, indicating characteristics of community-level factors (such as economic development and social capital) are important predictors of post-disaster mental health.Reference Schwartz, Rasul and Gargano 15 , Reference Lowe, Sampson and Gruebner 16
To examine whether hurricane and/or flood exposure increases negative mental health outcomes, we reviewed studies focused exclusively on populations exposed to either hurricanes or floods. We limited our analysis to US studies to account for consistent warnings from the National Weather System, uniform disaster relief resources, responses from Federal Emergency Management Agency, and standardized insurance regulations for natural hazard damage.
Objectives
We performed a systematic review and a meta-analysis of the evidence base of changes in depression, anxiety, and post-traumatic stress (PTS), along with other mental health outcomes in people impacted by hurricanes and floods. We sought to quantify the evidence of mental health impacts of exposure to hurricanes and floods in studies within the US where mental health outcomes were compared to pre-disaster measurements or unexposed controls.
Methods
The study protocol for this systematic review and meta-analysis was registered with PROSPERO (registration number 2021 CRD42021291101). Study design and reporting is guided by the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelinesReference Stroup, Berlin and Morton 17 and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist.Reference Page, McKenzie and Bossuyt 18 Quality assessment was performed using the New Castle-Ottawa Scale (NOS).Reference Wells, Shea and O’Connell 19
Study Identification and Selection
We conducted a systematic literature search for English-language research articles on mental disorders and/or suicide and hurricane and floods occurring in the United States published any time. The search was conducted in September 2021 and updated in March 2023 (Supplementary Tables S1 and S2 include details of the search criteria). We did not use restrictions on publication date to capture as many unique events as possible.
Study Inclusion and Study Selection
We included peer-reviewed articles where the study population experienced exposure to a hurricane, storm, and/or flooding, and the design included measurement of at least 1 psychological measure assessed in people affected by disaster, compared with an unaffected comparison group or a pre-disaster assessment in the same person. Articles including interventions, participants under age 10, commentaries, and reviews or articles not in English were excluded (Supplemental Table 1).
Reviewers (VM, KF, MS, EA) used Covidence software (Covidence, Veritas Health Innovation, Melbourne, Australia) to screen 6758 abstracts for inclusion. Data extraction was performed independently by VM, with 50% of studies selected by duplication of, and independently reviewed by, KF, MS, and EA. Conflicts were resolved by group consensus.
Quality Assessment
Quality assessment of articles was performed (by VM, and duplicated by KF, MM, and IA) using the Newcastle-Ottawa Scale (NOS).Reference Wells, Shea and O’Connell 19 Criteria for evaluating case-control studies, cross-sectional, and longitudinal studies were used to classify studies into high, medium, or low risk of bias based on NOS cumulative scoring.
Effect Measures
We extracted mean scores from validated scales measuring mental health outcomes. The construct measured (depression, anxiety, PTS, or other mental health outcomes), instrument, mean score, and standard deviation were extracted for the unexposed group (or pre-disaster group) and the exposed group (or post-disaster group), along with the number of people in each group (see Supplemental Table 3 for example data extraction).
Meta-Analysis Model
Due to variability in instruments used to assess depression, anxiety, and PTS, we used standardized mean difference (SMD) estimates with 95% confidence intervals to compare results across different instruments assessing the same psychological construct.
To assess the association between hurricanes and floods and each of the 3 outcomes, we calculated an overall effect size for each outcome by applying a random-effects model to mean scores. A random-effects model was applied to analyze pooled means scores by mental health outcome. Heterogeneity was assessed and forest plots with 95% confidence intervals were produced for all studies that reported key outcomes with means and standard deviations. Standardized mean differences (Hedge’s g) range from 0 to 1. We used the commonly prescribed cut points of Hedge’s g at 0.20, 0.50, and 0.80 to describe small, medium, and large effect, respectively.Reference Cohen 20
Variability between studies was assessed with the calculation of I2, measuring heterogeneity across meta-analyses, the standard deviation tau (τ) and variance of heterogeneity τ2 to measure the total amount of systematic differences in effects across studies.Reference Higgins, Thompson and Deeks 21 I2 is often presented as a ratio of true heterogeneity to total variance across the observed effect estimates. A small value of I2 indicates the effect size is comparable across studies in the meta-analysis, and a larger I2 signals substantial difference across studies.Reference Borenstein, Higgins and Hedges 22 I2 values range from 0-100, with suggested benchmarks of 25%, 50%, and 75% as low, moderate, and high.Reference Borenstein, Hedges and Higgins 23 , Reference Higgins, Thompson and Deeks 24 The meta-analysis was conducted using Stata (Stata Corp, Texas Station). The meta-analysis models included subgrouping by study design. We followed guidance to not visually assess funnel plots for publication bias under these conditions.Reference Ioannidis and Trikalinos 25 Separate analyses were conducted restricting studies to only those that measured outcomes within 12 months of the hurricane or flood.
Results
Study Selection
We identified 7742 abstracts and performed full-text review of 859 articles (Figure 1). Of the 859 articles, 25 articles met stated inclusion criteria with responses from a combined total of n = 616 657 people (Table 1).
Figure 1. PRISMA flowchart of study selection. PRISMA flow chart of study selection for systematic review of the association between hurricane and flooding disasters and psychological distress. Contact with authors was not made due to the length of time since publication.
Table 1. Studies included in review presented by study type, n = 25
NR, Not Reported; PHQ-9, Patient Health Questionnaire-9; PSQW, Penn State Worry Questionnaire; PCL-C, Post-traumatic Checklist-Civilian; DASS, Depression, Anxiety and Stress Scale; Zung SDS, Zung Self-Rating Depression Scale; SCL-90, Symptom Checklist; BDI, Beck Depression Inventory; CES-D, Center for Epidemiologic Studies Depression Scale; IES-R, Impact of Events Scale-Revised; RCMAS, Revised Children’s Manifest Anxiety Scale; CAPS, Clinician administered PTSD scale; SDQ, Strengths and Difficulties Questionnaire; SF-36, Short Form 36; RCADS, Revised Child Anxiety and Depression Scales, Child and Parent Version; PSS, Perceived Stress Scale; K6, Kessler Psychological Distress Scale; RCMAS, Revised Children’s Manifest Anxiety Scale; RCADS-MD, Revised Child Anxiety and Depression Scales, Major Depression; RCADS-GA, Revised Child Anxiety and Depression Scales, Generalized Anxiety
Study Characteristics
Eight case-control studies,Reference Cherry, De Vito and Calamia 26 ‒Reference Walling, Tucker and Pfefferbaum 33 12 cohort studies, and 6 cross-sectional or panel studies contained a valid control group and an assessment of a mental health outcome. The most assessed outcome was depression (n = 13 studies), 8 studies assessed anxiety, and 7 studies measured PTS (Table 1).
More than half of the studies in the sample (n = 17) focused on the 2005 disaster Hurricane Katrina (Global identifier number [GLIDE] #TC-2005-000144-USA), 3 of which also included Hurricane Rita (GLIDE #TC-2005-000163-USA), which made landfall in the month following Hurricane Katrina, exposing many people to 2 storms. Four studies concentrated on other hurricanes or tropical storms (Hurricane Andrew [GLIDE #TC-1992-000002-USA], Hurricane Michael [GLIDE #TC-2018-000433-USA], Hurricane Maria [GLIDE #TC-2018-000433-USA] and Tropical Storm/Hurricane Agnes [GLIDE #TC-1972-000002-USA]). The remaining 4 studies focused on flooding in Baton Rouge, LA (GLIDE #FL-2016-000145-USA), Puerto Rico (1985), North Dakota (1997), and Iowa (FL-1993-000005-USA). Global identifiers were not available for the flooding in Puerto Rico in 1985 and North Dakota in 1997.
Quality Assessment
Seven studies were rated as low risk of bias/high quality, 3 of these were case-control studies (Table 1). Five studies received a medium quality rating, 3 of which were case-control studies. The remaining studies (n = 13) were rated as high risk of bias/low quality or unable to assess. Typical issues of quality assessment were lack of a reported response rate, lack of information about missing values, and questions about the representativeness of the cases in case-control studies. One study reporting attrition in the sample found that only 30% of the original sample was able to be located and assessed for follow up.Reference Costa, Weems and Pina 34 Unfortunately, this study was one of the few that reported pre- and post-PTS symptoms assessments in a cohort. Pre-disaster assessments were performed in a range from less than 1 monthReference Vu and Vanlandingham 35 to 2 years before disaster.Reference Kessler, Galea and Jones 36 Post-disaster assessments were performed in a range from 1 monthReference Ginexi, Weihs and Simmens 28 , Reference Brown, Cherry and Marks 37 to 5 years after disaster,Reference Melick and Logue 29 , Reference Abramson, Park and Stehling-Ariza 38 and 2Reference Cherry, De Vito and Calamia 26 , Reference Zahran, Peek and Snodgrass 39 studies failed to report the time of assessment relative to disaster.
Exposure Assessment
The primary method of exposure assessment was geographic (n = 14 studies), with descriptions ranging from state-level to residence within a 40-mile (64.4 km) radius of the storm path. Among these, 6 studies also assessed self-reported disaster exposure. Four studies recruited individuals displaced by flooding or storm damage, with some case-control studies recruiting participants directly from relocation camps. Seven studies utilized self-reported exposure measures, all incorporating standardized instruments for reporting of traumatic events experienced during or after a disaster, such as the Hurricane-Related Traumatic Experiences QuestionnaireReference La Greca, Silverman and Wasserstein 40 or the Survey of Exposure to Hurricanes and their Aftermath.Reference Costa, Weems and Pina 34
Depression
Out of 25 studies, 13 (52%) measured depression for a combined population of n = 4086 people. Study sample sizes ranged from 42 to 1735 participants. Studies assessing depression included 6 case-control designs, 5 cohort studies, and 2 cross-sectional mean comparison studies. Eight studies were excluded from the meta-analysis; studies were excluded when either the authors did not report both mean and standard deviation estimates, and/or the authors only reported the percent of people who met a pre-specified cut-point. For example, FerraroReference Ferraro, Morton and Knutson 41 reported that 8% and 9.5% of the sample were diagnosed with depression pre- and post-disaster, respectively. The most used instrument was the Center for Epidemiologic Studies Depression scale (CES-D), used by 4 studies. Ten studies (77%) reported increased depression scores in people who were exposed to disasters. Twelve studies included information about the length of time between the hurricane or flood and assessment; the minimum time was 1 month, the maximum time was 60 months (mean = 13 months, SD = 15 months). Regarding quality assessment, all studies that reported an increase in depression in people exposed to flooding or hurricanes were assessed as low or medium risk of bias.
Anxiety
Nine studies measured anxiety with a total of n = 1447 individuals and sample size ranging from 52 to 392 people. Six studies included anxiety assessments that met inclusion criteria for the meta-analysis. One study was excluded because the anxiety measure (the Perceived Stress Scale) was reported as prevalence of the sample with a score above a cutoff score of 7, with 20% of the cohort meeting this threshold 1 year before hurricane exposure; 31% met this criteria between 7-19 months after exposure.Reference Rhodes, Chan and Paxson 42 Another excluded study reported higher scores on the Symptom Checklist (SCL-90) Anxiety subscale in controls compared to Tropical Storm Agnes exposed cases (scores 17 vs. 15, respectively), but standard deviations were not reported.Reference Melick and Logue 29 Also excluded was a study in which the authors reported the results of the Depression, Anxiety and Stress Scale (DASS-21) as a single score instead of reporting the anxiety subscale.Reference Fincham and May 43 The authors reported a decrease in the single summary score indicating a decrease in depression, anxiety, and stress in the time period after exposure to Hurricane Michael. Fifty percent of studies assessing anxiety enrolled children older than 10 or adolescents. The mean age of participants ranged from 11.3 yearsReference Costa, Weems and Pina 34 , Reference Weems, Pina and Costa 44 to 49.6 years,Reference Cherry, De Vito and Calamia 26 and 1 study enrolled fourth through sixth grade children but did not include a mean age of the sample.Reference La Greca, Silverman and Wasserstein 40 Four studies of 9 assessing anxiety reported increased anxiety in those exposed to disaster, 1 study reported no difference between the 2 groups, and 3 studies found lower anxiety scores in exposed relative to controls or pre-disaster comparisons. However, out of these 4 studies which reported an increase in symptoms, only 1 was assessed as having low risk of bias.Reference Vigil 32
Post-Traumatic Stress
Eight studies measured PTS, 6 of which were included in the meta-analysis. Of the 2 studies not included in the meta-analysis, 1 reported an increase in PTS in unexposed compared with exposed persons, but did not report standard deviations along with mean scores,Reference Walling, Tucker and Pfefferbaum 33 and the other study did not report mean scores from the PTSD Checklist for Civilians (PCL-C), but reported no difference in scores in people who were exposed compared to the unexposed.Reference McLeish and Del Ben 45 Two cohort studies (both assessing people exposed to Hurricane Katrina less than 1 year after the hurricane) performed pre-disaster and post-disaster assessment of PTS, but the studies had divergent findings. One study found an increase in PTS symptoms in youths and their parentsReference Costa, Weems and Pina 34 while another study found no increase in PTS in adolescents.Reference Weems, Pina and Costa 44 Four case-control studies found an increase in PTS in the exposed compared to the unexposed.Reference Cherry, De Vito and Calamia 26 , Reference Tucker, Pfefferbaum and Khan 31 ‒Reference Walling, Tucker and Pfefferbaum 33 Only studies that conducted diagnostic interviewsReference Canino, Rubio-Stipec and Bravo 46 specifically stated that the outcome of interest was related to hurricane or flood experience. Standardized questionnaires like the PCL-C do not specify an index event but instead ask about PTS symptoms in the previous 30 days.Reference Ruggiero, Ben and Scotti 47
Global Mental Health Status and Other Outcomes
Several studies included global measures of mental health status, such as results from the Kessler Screening Scale for Psychological Distress (K6), the mental composite score from the SF-36, number of poor mental health days, and suicide behavior. None of these studies were included in the meta-analysis due to small numbers and inconsistent reporting. Two cohort studies found increased prevalence of psychological distress defined by K6 scores above pre-defined cut-points in the post-exposure groups.Reference Rhodes, Chan and Paxson 42 , Reference Arkin, Lowe and Poon 48 One study used K6 scores pre- and post-Hurricane Katrina in 1849 people and found increased prevalence of severe mental illness post-hurricane (6.1% to 11.3%) and increased mild-moderate mental illness (15.7% to 31.2%).Reference Kessler, Galea and Jones 36 This study was the only one to include suicide-related outcomes. The authors found that in people with serious mental illness, the prevalence of suicidal ideation decreased from 8.4% pre-Katrina to 0.7% post-Katrina, and suicide plans dropped from 3.6% to 0.4%, while no difference was found in the percentage of people reporting a suicide attempt, which the authors hypothesize could reflect protective factors activated by the hurricane.Reference Kessler, Galea and Jones 36 Two studies reported an increase in the psychological SF-36 Mental Health Composite Score (MCS), indicating an increase in negative mental health symptoms, but increases were small and not statistically significant.Reference Vu and Vanlandingham 35 , Reference Brown, Cherry and Marks 37 One case-control study observed a decrease in the MCS, indicating improved mental health in people unexposed to a hurricane.Reference Stanko 30 Three studies used cross-sectional panel data to compare the number of poor mental health days or mental distress days, with 2 studies finding small increases in poor mental health days in geographic regions impacted by Hurricane Katrina.Reference Zahran, Peek and Snodgrass 39 , Reference An, Qiu and Xiang 49 A study using statewide data from Louisiana found a decrease in the population reporting no mental distress days from 76% to 69% comparing the year prior to Hurricanes Katrina and Rita to the year after the storms.Reference Mukherjee, Canterberry and Yore 50
Meta-Analysis of Depression, Anxiety, and PTS
Eleven of the 25 studies were included in the meta-analysis. Reasons for excluding studies were: (1) not including standard deviations along with means for groups;Reference Melick and Logue 29 , Reference Ferraro, Morton and Knutson 41 , Reference An, Qiu and Xiang 49 , Reference Hutchins and Norris 51 (2) reporting percentages representing prevalence;Reference Walling, Tucker and Pfefferbaum 33 , Reference Vu and Vanlandingham 35 , Reference Kessler, Galea and Jones 36 , Reference Abramson, Park and Stehling-Ariza 38 , Reference Rhodes, Chan and Paxson 42 , Reference Mukherjee, Canterberry and Yore 50 and (3) reporting only a global mental health status score.Reference Brown, Cherry and Marks 37 , Reference Zahran, Peek and Snodgrass 39 Overall, results of the meta-analysis suggest there was evidence of increased depression and PTS symptoms in people with disaster exposure, but no evidence for a change in anxiety symptoms. Results of the meta-analysis found depression scores were increased in those who were exposed to a disaster compared to the unexposed (k = 9; g = 0.28; 95% CI 0.04, 0.53). There was high heterogeneity in effect sizes in studies: I2 = 88.5%, τ2 = 0.17, Qresid (8) = 33.9, P < 0.01 (Figure 2). The meta-analysis resulted in no meaningful change in anxiety scores associated with disaster exposure (k = 6; g = -0.05; 95% CI −0.30, 0.19). There was moderate heterogeneity in effect sizes across studies: I2 = 69%, τ2 = 0.06, Qresid (5) = 15.73, P < 0.01 (Figure 3).
Figure 2. Studies assessing depression symptoms (n = 9), grouped by study design.
Figure 3. Studies assessing anxiety symptoms (n = 6), grouped by study design.
Regarding disaster exposure and PTS (Figure 4), exposure was associated with increased PTS (k = 6; g = 0.44; 95% CI 0.13, 0.76). There was high heterogeneity in effect sizes across studies of PTS symptoms: I2 = 76%, τ2 = 0.11, Qresid (5) = 17.57, P = 0.0035.
Figure 4. Studies assessing PTSD symptoms (n = 6), grouped by study design.
Sensitivity analyses
After excluding 1 study that assessed participants more than 12 months after exposure, the association with depression changed from g = 0.82 (95% CI 0.04, 0.53) to g = 0.15 (95% CI −0.085, 0.375). Repeating the meta-analysis for anxiety after excluding 1 study, altered the result from g = −0.05 (95% CI −0.30, 0.19) to g = −0.12; (95% CI −0.37, 0.12). Excluding 2 studies from the PTS meta-analysis, left 4 studies, changing the association with PTS symptoms from g = 0.44 (95% CI 0.13, 0.76) to g = 0.27; 95% CI −0.01, 0.54).
Discussion
Summary of Meta-Analysis Findings
In this meta-analysis we reported differences in mental health outcomes in persons exposed to hurricane and flood disasters. We restricted our review to include only research studied with findings based on an unexposed control group or a pre-post design for adequate comparison after previous systematic reviews research identified methodological limitation.Reference Sharpe and Davison 12 , Reference Flores, Sullivan and Yu 52 ‒Reference Deglon, Dalvie and Abrams 54 We found an increase in PTS symptoms and depression when comparing unexposed and exposed groups, but no meaningful difference in anxiety scores. Results of recent publications using meta-analyses have summarized results varying from no effect of disasters on mental health outcomes, to a small or medium effect.Reference Sharpe and Davison 12 , Reference Rubens, Felix and Hambrick 13 , Reference Flores, Sullivan and Yu 52 , Reference Huang, Gao and Xu 53 , Reference Powell, Wegmann and Backode 56 , Reference Felix, Rubens and Hambrick 57 –Reference Golitaleb, Mazaheri and Bonyadi 59 One meta-analysis including multiple study types and multiple disaster types found a point estimate of mental health disorders after flood disaster across 9 countries to be 7%, and prevalence of PTSD to be between 3% and 52%.Reference Keya, Leela and Habib 55 A meta-analysis focused on flood survivors experiencing PTSD estimated the prevalence to be 29%, but none of the included studies were from the United States.Reference Golitaleb, Mazaheri and Bonyadi 59 Our findings are consistent with those of Beaglehole et al.,Reference Beaglehole, Mulder and Frampton 14 who performed a meta-analysis of studies measuring psychological distress after any type of disaster, and found a standardized mean difference between exposed and non-exposed groups or pre- and post-groups to be 0.63 (95% CI 0.27, 0.98). However, a limitation of previous studies is the use of any mental health outcome under the umbrella of “psychological distress,” while our study identified each outcome separately to disentangle differences across these outcomes. Our study adds focus on 3 major psychological symptoms (depression, anxiety, and PTS) and was limited to hurricanes and floods within the United States. The variability in our meta-analytic findings and the heterogeneity in these studies reflects the complexity of measuring psychological outcomes in different populations and emphasizes the uniqueness of psychological constructs of depression, anxiety, and PTS.
Interpretation
This finding supports the conclusion that depression and PTS are elevated in hurricane and flood survivors. The meta-analytic finding suggests a moderate effect size for PTS symptoms, with lower effect size for depression, and no effect in assessment of anxiety. The assumption underlying the interpretation of the standardized effect size Hedges’ g is that if all mean scores were transformed to a scale where the standard deviation is equal to 1 within-groups, then we expect to see an increase in PTS in the exposed compared to the unexposed of 0.44 on this scale. The larger effect size for PTS compared with depression or anxiety might be due to PTS questionnaires assessing symptoms that do not map onto anxiety and depression, and those symptoms (detachment, re-experiencing) may account for the difference.
Mean differences were larger in case-control studies compared to cohort studies. It is not clear which studies informed participants about the goal of the study, indicating the potential participants in case-control studies could be subject to recall bias, with people experiencing hazards more likely to notice psychological symptoms and attribute changes in mental health as related to disaster exposure.Reference Norris 60 Cohort studies are not immune to bias; exposed participants could have been more likely to report psychological symptoms. Attrition of participants is a large problem for follow-up when populations have been displaced or displacement occurs differentially, introducing bias when those who are most vulnerable to poor mental health may also be those who are most vulnerable to displacement and severe disruption. The degree to which post-traumatic growth mediates the development of negative mental health outcomes in those exposed to disaster is outside the scope of this review, but studies have explored the complex relationship among psychological factors that decrease negative psychological outcomes in those who experience traumatic exposures.Reference Liu, Xu and Liu 61 , Reference Hikichi, Taku and Aida 62 Similarly, studies that assessed PTS did not clearly define an index event of traumatic exposure and given the prevalence of PTS prior to hurricane or flood exposure, therefore it is difficult to determine if individuals were responding to questions about symptoms related to exposure to a hurricane or flood, or if they were reporting symptoms beginning after an unrelated traumatic event.
Studies included in this systematic review assessed outcomes at varying lengths of time after the disaster. These differences in time to assessment make comparisons challenging. We performed additional analysis restricted to studies that only included assessments less than 12 months after the exposure. Findings from these additional analyses resulted in no statistically significant finding of the association between exposure to hurricanes and/or floods and the outcomes of depression, anxiety, or PTS. The change in point estimates for studies measuring PTS suggests that PTS symptoms could take longer to develop, or suggest individuals experienced sustained trauma over time (such as displacement or continued financial hardship).
Limitations
A lack of studies with low risk of bias was a limitation of the publications reviewed. Only 7 studies (28%) scored as low risk of bias according to our quality assessment. There were no studies included in the meta-analysis of anxiety or PTS with a sample size larger than 200 people. Conclusions based on a relatively small sample size should be approached with caution. Seventeen of 25 (68%) studies reviewed focused on Hurricane Katrina, including 6 of 11 (55%) studies included in the meta-analysis. This may provide a heterogeneous level of exposure that strengthens the findings but reduces generalizability to other hurricanes and floods impacting different regions.
In the absence of standardized assessment and reporting around the mental health impact of hurricanes and floods, our study is the best possible synthesis of the evidence base. Future research should structure post-disaster assessments around time-points that have clinical relevance for both the onset and the persistence of mental health outcomes. Future studies should focus on larger sample sizes; however, this recommendation requires deployment of prepared research strategies and “just-in-time” resources to mobilize data collection efforts. Of particular importance is the need to assess suicide-related outcomes.
Conclusion
Hurricanes and flooding cause significant loss of life, property, wages, and time, disrupting daily life for all ages. These events are linked to increased depression and PTS, and as climate change makes such events more frequent, the prevalence of related mental health issues is expected to rise. Differences in psychological outcomes highlight the need to measure depression, anxiety, and PTS separately, as each requires distinct therapeutic approaches. Tailored mental health interventions are crucial for helping survivors cope and rebuild. Enhancing mental health resources and awareness in hazard-prone areas may improve resilience.Reference Keya, Leela and Habib 55 , Reference Lowe, Bonumwezi and Valdespino-Hayden 58 Mental health support should be central to disaster preparedness and recovery efforts to prevent long-term disability and reduced quality of life.
Supplementary material
To view supplementary material for this article, please visit http://doi.org/10.1017/dmp.2024.327.
Acknowledgments
The research team would like to thank Karen Stanley Grigg for her assistance designing the search criteria from the UNC Health Sciences library.
Funding statement
Financially supported by the National Institutes of Health, National Institute of Mental Health, 5-R01MH124752.
Competing interest
The authors report no conflicts of interest.
