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Table of Contents
Year : 2022  |  Volume : 11  |  Issue : 1  |  Page : 1-5

Flood and hypertension: A systematic review

1 Prehospital Emergency and Disaster Management Center, Mazandaran University of Medical Sciences, Sari, Iran
2 Department of Emergency Medicine, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
3 Department of Geography and Urban Planning, Faculty of Literature, Humanities and Social Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
4 Department of Health Management, Sari Unit of Islamic Azad University, Sari, Iran
5 Health Management and Economics Research Center, Iran University of Medical Sciences, Tehran, Iran

Date of Submission26-Nov-2021
Date of Decision21-Jan-2022
Date of Acceptance26-Jan-2022
Date of Web Publication29-Mar-2022

Correspondence Address:
Mrs. Fariba Ghasemihamedani
Mazandaran Red Crescent Society, Imam-Reza Blvd., Sari
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/rcm.rcm_59_21

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Background: Several studies have been conducted on the effects of floods on the health of the affected community. We aimed to determine the effects of floods as the most common disaster on hypertension (HTN) as one of the most common noncommunicable diseases (NCDs). Materials and Methods: Four databases including Medline, Scopus, Google Scholar, and ScienceDirect were searched with the search strategy protocol up to the end of June 2021 and with the keywords of flood and high blood pressure or hypertension. Grey literature database and websites of WHO, UNDRR, and PreventionWeb were also searched. After removing duplicate articles, abstracts of the relevant titles were reviewed, and eligible articles were included for full-text review. Finally, the study variables were extracted from selected articles. Results: The search strategy resulted in eight final relevant articles from 48,980 articles. All final articles noted meaningful effect of flood on high blood pressure. There was a positive correlation between anxiety level, property loss, financial loss, physical activity, use of alcoholic beverages, interruption of medication, and medical cares with HTN. Different studies have also reported long-term effects of flooding on blood pressure. Conclusions: The flood has significant effect on high blood pressure in affected population. However, cases of unknown HTN in the affected population should also be considered, so screening is recommended in the affected community.

Keywords: Blood pressure, disaster, flood, hypertension

How to cite this article:
Habibisaravi R, Assadi T, Gholami G, Hasani M, Pourmand S, Navaie R, Ghasemihamedani F. Flood and hypertension: A systematic review. Res Cardiovasc Med 2022;11:1-5

How to cite this URL:
Habibisaravi R, Assadi T, Gholami G, Hasani M, Pourmand S, Navaie R, Ghasemihamedani F. Flood and hypertension: A systematic review. Res Cardiovasc Med [serial online] 2022 [cited 2022 May 23];11:1-5. Available from: https://www.rcvmonline.com/text.asp?2022/11/1/1/341266

  Introduction Top

In recent 50 years, natural disasters occurred three times more often than before with increasingly bad consequences.[1] For example, disasters have resulted in roughly 700,000 deaths, over 1.4 million injured, and near 23 million people homeless.[2] Floods are the most frequent natural disaster around the world, with potential growing occurrences in the future due to the consequences of climate change.[3] Floods not only have short-term effects on human health but also pose long-term side effects, resulting from unhealthy living conditions and population displacement.[4]

Disasters create the conditions for disease to occur or worsen by destroying infrastructure and reducing access to essential living resources, including safe water and food, health-care facilities, and available resources.[5] These changes in life conditions pose a significant risk of diseases to affected population. Noncommunicable diseases (NCDs), especially those with a chronic nature, such as hypertension (HTN), are among a group of diseases that are greatly affected.[5] HTN or high blood pressure is an important health issue that markedly increases the risks of heart, brain, and kidney diseases. It is estimated that 1.28 billion adults aged 30–79 years around the world have HTN, which most of them (two-thirds) live in low- and middle-income countries.[6] Disasters cause the emergence of new cases or disruption of the treatment of chronic diseases, including high blood pressure, and affect the state of disease control.[7]

In recent years, several studies have been conducted on the effects of disasters, especially floods, on the health of the affected community. Although several studies have been performed on the effects of floods on the cardiovascular system (CVS), the current study seeks to determine the effects of floods as the most common disaster on HTN as one of the most common NCDs. It is hoped that the results of this study will pave the way for proper planning for better management of HTN in disasters.

  Materials and Methods Top

We developed a searching strategy, inclusion criteria, and exclusion criteria of studies. We have reported the process of our review and results according to the PRISMA guideline.

Research questions

The review aimed to answer the following questions:

  1. How many documents and what are the characteristics of the articles on the HTN and flood in terms of article type, study approach (qualitative or quantitative), study setting, population and samples, results, time period, and country or affiliation of first/corresponding authors?
  2. What are the consequences of flood on high blood pressure?


  1. A “disaster” is “an artificial or natural event that disrupts the affected community functions and results in widespread losses that are greater than community resources”[8]
  2. “HTN” is a chronic disease of the CVS characterized when blood pressure is too high. HTN is diagnosed if, when it is measured on 2 different days, the systolic blood pressure readings on both days is ≥140 mmHg and/or the diastolic blood pressure readings on both days is ≥90 mmHg.[6]

Inclusion criteria

  1. Articles that were published in peer-reviewed journals and had addressed blood pressure or HTN in the context of flood (as defined above)
  2. Articles in any format including editorials, case reports, and original research
  3. Books or guidelines had addressed HTN in the context of flood (as defined above).

Exclusion criteria

  1. All non-English articles, unless an English abstract was available
  2. Papers with abstracts that did not include enough information or were not accessible for extraction of the study variables.

Search strategy (data sources and literature search)

We searched four databases, including PubMed, Scopus, Google Scholar, and Science Direct. We searched the databases for retrieving published articles up to the end of June 2021. In addition, grey literature (“that which is produced on all levels of government, academics, business, and industry in print and electronic formats, but which is not controlled by commercial publishers.”) was searched through the “New York Academy of Medicine Grey Literature Reports.”[9] Websites of WHO, UNDRR, and PreventionWeb were also searched for relevant guidelines. We also reviewed the references of retrieved studies to identify additional articles.

We chose key terms and developed a search strategy based on the National Library of Medicine “Medical Subjects Headings.” The following search strategy was applied in the PubMed database: “(Flood [Title/Abstract]) AND (“High Blood pressure” OR “Hypertension”) [Title/Abstract]). For searching in other databases, we did it similar to the PubMed search strategy. Searched contents were limited to titles and abstracts of articles.

Study screening process

Primarily, the mentioned keywords were entered into the search box of databases, and the search was limited to abstracts and titles. The keywords search results were reviewed by members of the review team (GG, SP, MH, RN, and FG). The studies that met the inclusion criteria were included in the review. If there was any uncertainty for meeting the inclusion criteria, a decision was made based on the supervisory team consensus (RH, TA, and FG). Articles unrelated to the aim of the study were excluded. The remaining titles were entered into a Spreadsheet and sorted to exclude duplicates. In the next step, the abstracts of the selected titles were screened for their precise relevance to the aims of the study. The abstracts that met the inclusion criteria were included in the review. Abstracts that were not precisely relevant were excluded. The full texts of the remaining papers were downloaded from the databases. If an article was not available free of charge, we paid for access. Data extraction from selected articles, data sorting in tables, presentation of analysis results, and writing of the final report were also done (RH, TA, RN, and FG).

Data analysis and quality assessment

The finally included papers were evaluated by a member of the review team (RH, TA, and FG) using a data abstraction sheet developed by the research team. This data sheet included the study variables: name of the authors; title; study type; model/framework used for the study; study population; the study approach/aims; mark results/findings; limitations of the study; country of study; and the publication year. In the extraction of the study approach and aim, our first priority was the authors' statement. If the study approach was mentioned in the article, the data were included in our data abstraction sheet. If not, the review team used a consensus approach to decide whether the data should be included. The included studies were examined for quality assessment by using of Strengthening The Reporting of Observational Studies in Epidemiology checklist, with the score ranging from 0 to 34.[10] In this review, studies were classified into three groups according to their obtained score as weak quality, ranging from 0 to 12; moderate quality, ranging from 13 to 23; and high quality, ranging from 24 to 34 [Supplementary File 1].

Ethics and dissemination

We obtained the approval of the Human Research Ethics Committee (HREC) for the present study as follows: HREC number: IR.MAZUMS.REC.1398.5926 dated August 8, 2019.

  Results Top

Initially, 48,980 potentially relevant articles were identified. After a duplicate articles removal and with the title and abstract review, 24 articles were selected for full-text review. After reviewing the full text, 16 articles were rejected and 8 final relevant articles were included in data extraction [Figure 1].
Figure 1: The articles selecting process

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Quality assessment of studies

Based on the quality assessment, four studies were categorized as moderate and four studies were categorized as high level of quality.

The first study was performed in 1980 and the last one in 2016, with the most gap between 1980 and 2001. The most common data study type was cross-sectional/cohort (n = 6; 75%). All eight studies were conducted in different countries.

A total of 34 researchers have collaborated to write these 8 articles, with an average of 4 people per article. In considerable articles (4 studies, 50%), the gender of the sample was not specified, in three articles (37.5%), the samples were male and female, and in one article (12.5%), all samples were women [Table 1].
Table 1: Summary of the basic features of included studies

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Although there were many limitations in different studies such as small sample size, retrospective cohort study, reliability of self-reporting of HTN, selection bias, recall bias, and impossibility to long-term follow-up, there was generally positive correlation between anxiety level and the high blood pressure.

The other effective factors were of property loss, financial loss, subsequent financial difficulties, physical work, and use of alcoholic beverages as well as interruption of medication and medical cares.

Different studies have reported different long-term effects of flooding on blood pressure. Some found it effective for up to 5 years, and some reported that the incidence of high blood pressure decreased shortly after the flood.

  Discussion Top

According to the records and as far as we know, the present study is the only systematic review research that has been done exclusively on the effects of flood on blood pressure with the wide range of searched databases. Although the study of Gohardehi et al. emphasized the relationship between the higher prevalence of HTN in different types of disasters, they did not report any flood-related articles in their review.[17] The reason for this difference can be attributed to the more comprehensive database of Google Scholar as one of the sources used in our study.

New-onset hypertension

In different studies, a significant relationship was reported with the occurrence of HTN following flood exposure. The main cause of these problems was flood-related anxiety. As Logue et al. mentioned, anxiety may be resulted from property loss, financial loss, and subsequent financial difficulties. As Baxter et al. reported directly facing flood also cause considerable anxiety. As reported by Salazar et al., this factor will reduce its effects over time as the anxiety of flood victims decreases.

The meaningful correlation between the mental and physical state of flood survivors and HTN indicated the importance of proper planning to address in this issue. Many factors such as change in physical activity, use of alcoholic beverages, disaster-induced stress, change in diet, and displacement facilitate the development of HTN over the period following a flood.[18] Besides that, due to destroying access routes to medical care and drugs, the controlled cases of HTN may develop more advanced stages of the disease.[19] In addition, according to adverse effects of flood-related stress on individuals' blood pressure, psychological supports should be taken into account.[20] Due to the special nature of the psychological effects of floods and the persistence of its effects for a long time after its occurrence, continuous supportive measures are necessary.[4]

Although the effect of floods on the incidence of HTN has been shown, according to available statistics, not all cases of postflood HTN can be attributed to flood because a significant percentage of people are unaware of having high blood pressure before flood.[6] This important point should be considered in the interpretation of epidemiological findings related to prevalence of HTN caused by disasters. Another important point is samples composition that women greater than men in significant number of studies and should be considered in generalizing the results of these studies to the community.

Known cases of hypertension

Our study emphasized the importance of HTN cases management in survivors of flood as new patients or existing patients whose treatment was interrupted. The interruption of treatment of known cases of HTN arises from many factors such as inaccessibility to medication and health-care services due to closing paths, lack of medicine stockpile for disaster situation by patients, and providing inappropriate medical services.[13],[14] In this regard, inadequate nutritional conditions after the occurrence of disasters and the use of canned foods with high salt have a significant effect on exacerbating high blood pressure and improper control.[12],[15]

The availability of complete information on patients in the affected area and their electronic health records in the event of a disaster is very helpful in continuing their medical care.[21] Access to medical information of individuals when moving from the scene of the disaster is very high because the interruption of medication occurred more commonly in the people who were evacuated, especially in elderly.[13]

In using the information of studies on the effects of floods on blood pressure, their limitations including small sample size, reliability of self-reporting of HTN, recall bias, types of medications and the duration of interruption, measurement bias, quality of registered data, preference of women in sampling, and the accuracy of applied population denominators should be considered.

  Conclusion Top

This study found that the flood has actual effect on high blood pressure in affected population in comparison to the general population. All countries around the world spend significant financial resources on diagnosing, treating, and rehabbing the effects of high blood pressure as one of the most common NCDs.[22] Due to the conditions of the disaster-affected communities, trauma and infectious diseases are usually given priority, and NCDs such as HTN are usually ignored in the early stages.[17]

However, according to the patients with unknown HTN in the affected population before flood, epidemiological information should be interpreted with more caution. Access to medical history and medical health records of affected population in the time of disaster happening is very helpful to better planning and to avoiding disruption in medication. Due to the serious burden of HTN, screening studies are recommended in the affected community.[23]

Ethics approval and consent to participate

We obtained the approval of the HREC for the present study as follows: HREC number: IR.MAZUMS.REC.1398.5926 dated August 8, 2019.

Financial support and sponsorship

This study has been funded and supported deputy of research of Mazandaran University of Medical Sciences, Contract No. 5926. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Conflicts of interest

There are no conflicts of interest.

  References Top

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United Nations. UNISDR, Sendai Framework for Disaster Risk Reduction 2015-2030. Sendai, Japan: UNISDR; 2015.  Back to cited text no. 2
Kundzewicz ZW, Kanae S, Seneviratne SI, Handmer J, Nicholls N, Peduzzi P, et al. Flood risk and climate change: Global and regional perspectives. Hydrol Sci J 2014;59:1-28.  Back to cited text no. 3
Seyedin H, HabibiSaravi R, Djenab VH, Hamedani FG. Psychological sequels of flood on residents of southeast Caspian region. Nat Hazards 2017;88:965-75.  Back to cited text no. 4
Salazar MA, Pesigan A, Law R, Winkler V. Post-disaster health impact of natural hazards in the Philippines in 2013. Glob Health Action 2016;9:31320.  Back to cited text no. 5
Hypertension; 2021. Available from: https://www.who.int/news-room/ fact-sheets/detail/hypertension. [Last accessed on 2021 Mar 18].  Back to cited text no. 6
Murakami H, Akashi H, Noda S, Mizoue T, Okazaki O, Ouchi Y, et al. A cross-sectional survey of blood pressure of a coastal city's resident victims of the 2011 Tohoku tsunami. Am J Hypertens 2013;26:799-807.  Back to cited text no. 7
Disaster Risk Reduction. UNISDR Terminology on Disaster Risk Reduction. United Nations Office for Disaster Risk Reduction 2009.  Back to cited text no. 8
Zhong S, Yang L, Toloo S, Wang Z, Tong S, Sun X, et al. The long-term physical and psychological health impacts of flooding: A systematic mapping. Sci Total Environ 2018;626:165-94.  Back to cited text no. 9
Vandenbroucke JP, von Elm E, Altman DG, Gøtzsche PC, Mulrow CD, Pocock SJ, et al. Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): Explanation and elaboration. PLoS Med 2007;4:e297.  Back to cited text no. 10
Logue JN, Hansen H. A case-control study of hypertensive women in a post-disaster community: Wyoming Valley, Pennsylvania. J Human Stress 1980;6:28-34.  Back to cited text no. 11
Baxter P, Moller I, Spencer T, Tapsell S. Health Effects of Climate Change in the UK: An Expert Review for Comment. London: Department of Health; 2001. p. 177-87.  Back to cited text no. 12
Tomio J, Sato H, Mizumura H. Interruption of medication among outpatients with chronic conditions after a flood. Prehosp Disaster Med 2010;25:42-50.  Back to cited text no. 13
Bich TH, Quang LN, Ha le TT, Hanh TT, Guha-Sapir D. Impacts of flood on health: Epidemiologic evidence from Hanoi, Vietnam. Glob Health Action 2011;4:6356.  Back to cited text no. 14
Joob B, Wiwanitkit V. Big flooding in Thailand, the problem on loss following up of patients with hypertension. Anadolu Kardiyol Derg 2012;12:283-4.  Back to cited text no. 15
Phalkey R, Dash SR, Mukhopadhyay A, Runge-Ranzinger S, Marx M. Prepared to react? Assessing the functional capacity of the primary health care system in rural Orissa, India to respond to the devastating flood of September 2008. Glob Health Action 2012;5:10964.  Back to cited text no. 16
Gohardehi F, Seyedin H, Moslehi S. Prevalence rate of diabetes and hypertension in disaster-exposed populations: A systematic review and meta-analysis. Ethiop J Health Sci 2020;30:439-48.  Back to cited text no. 17
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Vanasse A, Cohen A, Courteau J, Bergeron P, Dault R, Gosselin P, et al. Association between floods and acute cardiovascular diseases: A population-based cohort study using a geographic information system approach. Int J Environ Res Public Health 2016;13:168.  Back to cited text no. 19
Azuma K, Ikeda K, Kagi N, Yanagi U, Hasegawa K, Osawa H. Effects of water-damaged homes after flooding: Health status of the residents and the environmental risk factors. Int J Environ Health Res 2014;24:158-75.  Back to cited text no. 20
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Egan BM, Kjeldsen SE, Grassi G, Esler M, Mancia G. The global burden of hypertension exceeds 1.4 billion people: Should a systolic blood pressure target below 130 become the universal standard? J Hypertens 2019;37:1148-53.  Back to cited text no. 22
Von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP, et al. Strengthening the reporting of observational studies in epidemiology (STROBE) statement: Guidelines for reporting observational studies. BMJ 2007;335:806–8.  Back to cited text no. 23


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