Skip to main content
Advertisement
Browse Subject Areas
?

Click through the PLOS taxonomy to find articles in your field.

For more information about PLOS Subject Areas, click here.

  • Loading metrics

Fatal intentional drowning in Australia: A systematic literature review of rates and risk factors

  • Muthia Cenderadewi,

    Roles Conceptualization, Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review & editing

    Affiliation College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia

  • Richard C. Franklin ,

    Roles Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, Writing – original draft, Writing – review & editing

    richard.franklin@jcu.edu.au

    Affiliations College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia, Royal Life Saving Society—Australia, Sydney, Australia

  • Amy E. Peden,

    Roles Project administration, Writing – review & editing

    Affiliations College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia, Royal Life Saving Society—Australia, Sydney, Australia, School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia

  • Sue Devine

    Roles Project administration, Writing – review & editing

    Affiliation College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia

Abstract

Introduction

Unintentional drowning deaths are only part of the drowning profile, with little attention being paid to intentional drowning in Australia. Strategies for the prevention of intentional drowning deaths are likely to be different from unintentional. Quality documentation, analysis and dissemination of intentional deaths data is crucial for developing appropriate strategies for prevention.

Objective

To conduct a systematic literature review to investigate the mortality rates and risk factors of intentional drowning deaths in Australia.

Methods

A systematic search guided by PRISMA was performed using Ovid MEDLINE, CINAHL, PsycINFO (ProQuest), Scopus, Google Scholar, and BioMed Central databases to locate relevant original research articles published between 2007 and 2018.

Results

Ten papers reporting the mortality rates and risk factors of intentional drowning deaths in Australia published between 2007 and 2018, with study periods of the included articles spanning from 1907 to 2012, were reviewed. Most studies investigated suicidal drowning deaths in Australia, none reported homicidal drowning deaths. The downward trend of fatal suicide drowning was identified in Australia. The annual rate of intentional drowning between 1994 and 2012 can be inferred from eight studies, ranging from 0.06 to 0.21 for nation-wide mortality rates. The highest annual state-wide mortality rate was identified in the state of Queensland, ranging from 0.02 to 0.11 per 100,000 individuals. Of four studies examining the risk factors of fatal intentional drowning in Australia, being of older age groups, being female, and the presence of substance use were identified as important factors for suicidal drowning deaths. The national-scale proportion of suicide drowning in Australia, ranging from 2% to 3% of all intentional self-harm deaths, was also identified.

Conclusion

Limited publications reporting the mortality rates and risk factors of intentional drowning deaths in Australia were identified. Being of older age groups and being female were recognised as factors for suicide drowning deaths, and psychoactive substances were widely identified amongst cases. Future research on improving death reporting systems and the legal framework for medico-legal death investigation, along with the investigation of the risk factors of intentional drowning, are required to inform the planning, implementation, and evaluation of prevention interventions for intentional drowning deaths in Australia.

Introduction

Drowning is the third leading cause of unnatural deaths worldwide.[13] According to the World Health Organization (WHO) Global Report on Drowning, annually the lives of 320,000 people are lost due to drowning worldwide. [4] A recent study on the global, regional and national burden of unintentional drowning mortality from the Global Burden of Disease 2017 by Franklin et al, reported a global estimate of 295,210 fatalities was attributed to drowning in 2017.[1] However, the drowning statistics reported may underestimate the actual magnitude of all drowning deaths as has been suggested in several previous studies, particularly regarding unintentional drowning fatalities.[58] Peden et al [6] identified a 40% under-report between WHO methodology and unintentional fatal drowning in Australia. A similar study also estimated a 35% higher unintentional drowning mortality rate in Australia and the United States (US) when compared to WHO estimates, with other studies estimating a gap of 50%.[7] The recent study on the burden of unintentional drowning mortality from the Global Burden of Disease 2017, including in Australia, also did not include intentional drowning, which underlines the need for further study on intentional drowning deaths.[1]

Publications on the extent and trends of intentional drowning death are limited, even in high income countries where injury surveillance is better established than in developing nations.[9, 10] Most studies on intentional drowning explore suicides by drowning, with limited attention on submersion deaths due to assault.[9, 1120] Despite the limited number of publications, a high proportion of intentional drowning deaths were identified amongst all fatal drowning incidents reported in previous studies.[2126] A study in Sweden over the period of 1992–2009 [2], reported 31% of all drowning deaths in the country were identified as suicidal. In contrast to the disproportionately higher risk for unintentional drowning amongst male populations worldwide, more than half of suicide drowning cases were performed by females (55% versus 21%, p<0.001).[2, 27] The evidence on the proportion of intentional drowning of all suicidal deaths, however, shows varying proportions across the world. A study based in Milan, Italy, described suicidal drowning as the fifth highest cause of death due to self-harm registered in the region [11], while much lower proportions where identified in Norway (9%) [12], Canada (6%) [28], the US (1%) [15], and Taiwan (1%) [29].

As reported by the WHO in its 2012 publication ‘Public Health Action Framework For The Prevention Of Suicide’, death by suicide has been acknowledged as a major health issue throughout the world, with close to one million lives being lost due to suicide annually.[30] In 2015, suicide was the 10th and the 13th leading cause of death in the US and Australia, respectively. [31, 32] The trend of suicide deaths has also been consistently increasing, and the 2% contribution of suicide deaths to the global disease burden in 1998 is predicted to increase by one-third by 2020. The suicide mortality rate in Australia has also shown an upward trend, from 10 deaths per 100,000 individuals in 2006 to 14 deaths per 100,000 in 2015.[32] It is important to determine whether a similar trend is also observed for intentional suicide by drowning deaths in Australia. This will provide a better understanding of whether suicide drowning deaths have been contributing to the increasing trend of the suicide mortality rate in Australia, underlining the urgency of advocating for the enhancement of appropriate preventive measures for intentional drowning fatalities. This may differ from unintentional drowning prevention efforts.[32]

The link between suicidal drowning deaths and psychiatric disorders has also been reported in previous studies worldwide.[9, 3336] A study in South Korea by Woo et al, [37] reported 21% of intentional drowning deaths between 2000 and 2012 were documented with a history of depressive episodes; although other risk factors, including being widowed and being out of work-force, also contributed as important factors among older age groups. Thus, in the context of suicide prevention in Australia, particularly with the high burden of mental health disorders in Australia [3841] and the devastating impacts of intentional deaths [4245], it is essential to provide reliable information on the trend and rates of intentional drowning. Such information will inform the development, implementation and evaluation of intentional drowning prevention and mental health promotion strategies in Australia.

Through a systematic review of the literature this study aimed to describe the epidemiology, the mortality rates and risk factors of intentional drowning deaths in Australia (i.e. both suicide and assault). This study answers the following questions:

  • What is the mortality rate of intentional drowning in Australia?
  • What proportion of suicide mechanisms is drowning in Australia?
  • What are the risk factors for fatal intentional drowning in Australia?

Materials and methods

Search strategy

A systematic search was performed using six databases: 1) Ovid MEDLINE, 2) CINAHL, 3) PsycINFO (ProQuest), 4) Scopus, 5) Google Scholar, and 6) BioMed Central, to locate original research articles published between 2007 and 2018. The most exhaustive search strings (i.e. those that returned the highest number of results) were applied in the systematic search, in accordance to each database utilised (Table 1). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram [46] was used to report the systematic literature review process. The PRISMA checklist for this study can be found in S1 File.

Selection process.

The selection process of all identified records was as follows:

Title and abstract screening.

The titles and abstracts of all records identified through database searching were screened by the inclusion and exclusion criteria (outlined in Table 2), to ensure the relevance of the studies included for the evidence-based review. If a study examined both intentional and unintentional drowning cases, it was included if intentional drowning rates and risk factors could be differentiated from the unintentional cases.

Full-text screening.

The full-text version of the identified articles were then appraised to examine the methodological quality of the studies, using the McMaster appraisal guideline for quantitative and qualitative studies. [47] The PRISMA flow diagram below summarises the selection process of this review (Fig 1).

thumbnail
Fig 1. PRISMA flow diagram of the study selection process.

https://doi.org/10.1371/journal.pone.0231861.g001

Data abstraction

The following data were abstracted from the studies: year of study and publication, data source, study design, scale of study, manner of intentional drowning deaths investigated, and mortality rates and risk factors of intentional drowning in Australia.

The nation-wide annual rates of intentional drowning were then inferred from studies that report nation-wide suicide drowning deaths and sourced their data from national scale sources. Such sources included the Australian Bureau of Statistics (ABS), the Australian Institute of Health and Welfare (AIHW), the National Coronial Information System (NCIS), or news reports. Rates were inferred by extracting the number of intentional drowning deaths from the papers in proportion to the population of the said year based on Australian population data provided by the ABS.

Meanwhile, the studies which only reported state-wide rates of intentional drowning deaths were not included in the nation-wide mortality rate calculations. Instead, these state-wide rates were inferred by extracting the number of intentional drowning deaths in the state from the paper in proportion to the population of the corresponding state for the said year based on the ABS data.

Results

Electronic searches located a total of 574 articles from the six databases used, after duplicates were removed. Using the previously established inclusion and exclusion criteria (Table 2), titles and abstracts of identified records were reviewed, resulting in 552 articles excluded due to ineligibility. After critically assessing the methodological quality and relevance of the full texts of the remaining articles using the McMaster appraisal form [47], 10 articles [4857] were included for evidence-based review (Fig 1). Of ten articles included in this review, only one article [50] reported mortality rates of suicide drowning in Australia, while the majority of articles reviewed [4850, 5257] investigated suicidal drowning deaths in proportion to suicidal deaths of all causes in Australia. Amongst these, four articles [49, 50, 52, 53] also examined the risk factors of fatal intentional drowning in Australia. The full details of the data extraction, including any publication bias, can be found in S2 File.

Six articles [48, 50, 5355, 57] were nation-wide studies, while the remaining four [49, 51, 52, 56] were of subnational scale, with two studies from the state of Queensland [52, 56] identified. All ten studies in this review utilised primary data sources. Four articles investigated national health and demographic statistics, provided by either the ABS or the AIHW [48, 50, 54, 58]. Four studies relied on suicidal drowning deaths data available in the NCIS [5558] (Table 3). One study [54] used news reports as a data source, to determine the ‘news-worthiness’ of suicide deaths in Australia. Three studies [53, 54, 56] employed more than a single data source.

thumbnail
Table 3. Epidemiological data sources on intentional drowning mortality in Australia for studies included in this review.

https://doi.org/10.1371/journal.pone.0231861.t003

Intentional drowning rates in Australia

Of the ten publications reviewed in this study, nine studies [4850, 5257] investigated intentional drowning deaths in Australia, compared to the proportion of suicidal deaths of all causes. One paper [51] determined the incidence of both intentional and unintentional drowning, as described in Table 4. However, none of the studies included in this review examined drowning deaths due to assault (Table 4).

thumbnail
Table 4. The epidemiology of intentional drowning deaths in Australia.

https://doi.org/10.1371/journal.pone.0231861.t004

Only one study [50] reported mortality rates of suicide drowning in Australia, highlighting the downward trend of intentional drowning as the preferred suicide method over a 90-year period of time (Table 4). Investigating the trend of mortality by suicide in Australia over the period 1907–1998, Donaldson, Bi and Hiller, 2007 [50] reported the trend of suicide drowning has been decreasing, from 3.10/100,000 in 1907 to 1.00/100,000 in 1998 among males, and from 1.25/100,000 in 1907 to 0.30/100,000 in 1998 in females.

The annual nation-wide rates of intentional drowning between 2000 and 2012, can be inferred from four studies [48, 53, 54, 55] (Table 5). Rates ranged from 0.06 to 0.21 for nation-wide mortality (Table 5). Meanwhile, the annual state-wide mortality rates between 1994 and 2012 can be inferred for three states: New South Wales [49], Victoria [51] and Queensland [53, 54, 55]. The lowest annual state-wide mortality rate was identified in the state of Victoria, with 0.01/100,000 from 1999 to 2011, and the highest observed in Queensland, ranging from 0.02 to 0.11 per 100,000 individuals, as described in Table 5. In comparison to all intentional self-harm deaths in Australia, the proportions of suicide drowning ranged from 2.1% to 2.7% [48, 55]. However, a higher proportion was reported in the state of Queensland with 5.7% suicidal drowning deaths among all suicide deaths documented in the state [52] (Table 5).

thumbnail
Table 5. Inferred annual national- and state-wide mortality rates of intentional drowning in Australia between 1994 and 2012.

https://doi.org/10.1371/journal.pone.0231861.t005

Risk factors of intentional drowning in Australia

Of four articles [49, 50, 52, 53] examining the risk factors of fatal intentional drowning in Australia, socio-demographic characteristics, including age [52], gender [50], and substance use [53] were identified as important factors for suicidal drowning deaths. The highest incidence of suicidal drowning in Australia was observed in the older age groups of 65–74 and 75–84 years.[52] In fact, amongst older adults aged 65 years and over, the risk of intentional drowning in Australia significantly increased with age (χ2 trend = 5.95, df = 1, p = 0.02), with individuals aged 65 to 74 years 0.65 (95% CI: 0.36–1.17) times less likely to perform suicide by drowning than individuals aged 75 to 84 years.[52] One study [50] investigated rates and trends of fatal suicide drowning in Australia by gender, between 1907 and 1998. The study found drowning was the most commonly used suicide method by females in the beginning of the last century, with a rate of 1.25 per 100,000 individuals in 1907.[50] Although this preference changed over time with the rise of non-violent suicide methods, such as poisoning, drowning was still commonly used by females in Australia in 1998 with an annual rate of 0.30/100,000. [50] On the contrary, drowning was the least common suicide method used by male victims in Australia between 1907 and 1998.[50]

The omnipresence of psychoactive substances among suicidal drowning cases in Australia was reported by Darke, Duflou [49]. This study revealed 91.7% of suicide drowning cases between 1997 and 2006 tested positive for substances, including alcohol (52.8%), pharmaceuticals (47.2%), other illicit drugs (19.4%), psychostimulants (8.3%), cannabis (5.6%), and opioids (5.6%).

Discussion

This review aimed to describe the epidemiology, particularly the mortality rates and risk factors, of intentional drowning deaths in Australia. Ten publications on fatal intentional drowning in Australia were identified, with the majority of studies [4850, 5257] investigating suicidal drowning deaths in Australia, in proportion to suicidal deaths of all causes. No studies included drowning deaths due to assault, highlighting the lack of peer-reviewed publications on homicidal drowning deaths in Australia. This under-exploration of the epidemiology of intentional drowning deaths in Australia is similar to other developed nations, such as the US [15, 59, 60], the United Kingdom (UK) [14, 19, 61], Taiwan [17, 29, 62], Switzerland [6366], Austria [63, 67, 68], and Germany.[66, 69] Studies from these countries also reported fatal suicidal drowning in proportion to suicidal deaths by all methods. Sweden, on the other hand, has two comprehensive studies specifically investigating the rates and trends [2], and risk factors [9] of suicide drowning deaths, highlighting the importance of intentional drowning as a public health issue in the country. The dearth of epidemiological studies of intentional drowning deaths in high-income countries, including in Australia, underlines the gap between the more thoroughly understood epidemiology and advanced efforts of preventing unintentional drowning deaths, in comparison to the relatively under-exposed and under-represented intentional drowning deaths. This also highlights the possibility of further under-exploration of intentional drowning deaths in the resource-limited setting of developing nations, where injury surveillance systems, including for self-harm related events, might not be as well-developed as those available in high-income countries.[70, 71]

One study in this review [50], reported the trend of suicide drowning had been decreasing in Australia over the period 1907–1998. This downward trend of fatal suicide drowning is similar to several other high-income countries, for instance in Sweden [2] and Norway [12]. Thomas and Beech [14] also revealed the reduction of drowning as the preferred suicide method in England and Wales, from 23% of suicide deaths in 1901–1907 to 3% in 2001–2007, suggested restrictions to physical access, improvement in water transportation systems, and social preferences as factors influencing the changes in the popularity of some suicide methods. Although these data span a wide time period and are somewhat out of date now, this underlines the importance of modifying physical and social environments and developing mental health promotion to further reduce the risk for suicide drowning in the community.

This systematic literature review identified the national-scale proportion of suicide drowning in Australia ranging from 2% to 3% of all intentional self-harm deaths [48, 55]. These proportions of suicide drowning in Australia are comparatively lower than proportions observed in several other high-income countries including Germany [69], Sweden [72], and Switzerland [64]. It is also lower than the 16 European countries participating in the European Alliance Against Depression (EAAD) (Table 6).

thumbnail
Table 6. Comparison of suicide drowning in Australia to other high-income countries.

https://doi.org/10.1371/journal.pone.0231861.t006

There is a dearth of publications explaining the discrepancy between the lower proportion of suicide drowning among all suicide deaths in Australia in comparison to other developed nations. It is noted that there is a need for further research addressing the preference for suicide methods by countries, to inform the development of intervention strategies appropriate for each country, including Australia.

Risk factors of fatal suicide drowning in Australia

This review reveals the under-exploration of risk factors in relevance to the incidence of suicidal drowning deaths in Australia. This poses an obstacle to the development, planning, and implementation of intervention strategies for intentional drowning in Australia.

Fatal suicide drowning amongst elderly Australians.

Only one study in this review investigated age as a risk factor for intentional drowning deaths.[52] The risk of intentional drowning significantly increased with age (χ2 trend = 5.95, df = 1, p = 0.02), with the highest incidence of suicidal drowning observed in the older age groups of 65–74 and 75–84 years. [52] This is similar to findings of a previous study in Japan [20] and studies in England and Wales [13, 19, 61], where suicidal drowning was significantly higher in the older age group of 65 years or older than in individuals aged less than 65 years. Purandare et al, 2009 [61] contended that the choice of ‘less-violent’ suicide methods by older populations may be partially explained by aging-related cognitive deficits, potentially hindering the arrangement and enactment of the suicide act itself.

Suicide drowning deaths in Australia by gender.

From the limited available data, it appears that there is a higher proportion of intentional drowning deaths among females than males in Australia. Donaldson, Bi and Hiller, 2007 [50] reported drowning as one of the most preferred suicide methods among female Australians across an extensive period between 1907 and 1998, while it was the least common suicide method used by male victims throughout the study period. Higher proportions of female suicides by drowning, in comparison to proportions in male suicide deaths, were also reported in Croatia [73], UK [13], Norway [12], and Japan [18].

In comparison to unintentional drowning in Australia, the finding of higher proportion of intentional drowning deaths in females in this review is also distinct from the epidemiology of unintentional drowning deaths in Australia. [74] As reported by Franklin, Scarr and Pearn, 2010 [74], 77% of all unintentional drowning cases in Australia between 2002 and 2006 were in males, as well as 80% of unintentional fatal drowning in Australian rivers [75].

Psychoactive substances and fatal suicide drowning in Australia.

In this review, one study [49] identified psychoactive substances as a risk factor for intentional drowning and revealed the wide presence of psychoactive substances amongst suicidal drowning cases in Australia. Darke, Duflou and Torok, 2009 [49] reported those who died from suicide drowning in Australia were 2.56 times (95% CI: 1.24–5.29) more likely to be detected with benzodiazepines, and had 3.23 times (95% CI: 1.56–6.69) higher likelihood to be detected with antidepressants. This finding of the higher odds for benzodiazepines and antidepressants use amongst suicidal drowning victims is consistent with the report of the potential over-prescribing of benzodiazepine substances and antidepressants across Australia over the period of 1992 to 2011.[7681]

The under-exploration of psychiatric disorders among suicidal drowning victims in Australia.

None of the studies investigated in this current review explored the history of mental health disorders and previous suicide attempts amongst intentional drowning victims in Australia. This is despite the relevance of suicidal drowning deaths and psychiatric disorders identified in previous studies worldwide.[9, 3336] The high proportion of prior psychiatric admissions and suicide attempts amongst suicidal drowning victims was reported in Sweden, with half of suicide drowning victims having had a history of hospitalisations due to mental health conditions. [9] One-third were released or left hospital less than one week before the suicide, and one-third had a history of previous unsuccessful suicide attempts.[9]

It is relevant to acknowledge that this current review identified suicide by drowning as the preferred method of suicide in only 2% to 3% of all intentional self-harm deaths in Australia. This highlights the importance of early recognition of mental disorders and previous suicide attempts, as well as the enhancement of mental health promotion and deliberate self-harm prevention, as a part of intentional self-harm and suicide prevention strategies, including for suicide by drowning.[9, 16, 18, 29, 64, 71, 73, 82]

Recommendations for future research

This review has highlighted several opportunities for future research, with a particular focus on improving data collection systems for intentional drowning deaths and investigating risk factors of intentional drowning. Such research will inform the planning, implementation, and evaluation of intentional drowning prevention.[4, 83, 84]

Improving data collection systems.

There are challenges in investigating intentional drowning deaths, such as: (1) the difficulty in determining the intent of death, related to the legal framework and medico-legal investigation required to determine the manner of unnatural deaths, (2) the availability of a functioning national death registration system that records the causes of and circumstances surrounding the event of death, and (3) the availability of coding system with an appropriate level of detail for additional causes of death and co-morbidities to enable the investigation of the risk factors of intentional drowning death. [2, 8589] These factors, as outlined in Fig 2, need to be strengthened in order to improve intentional drowning data collection, analysis, and dissemination to inform prevention strategies.

thumbnail
Fig 2. Future research needed for improving intentional drowning data collection systems.

https://doi.org/10.1371/journal.pone.0231861.g002

Investigating risk factors of intentional drowning.

Another gap identified in this review is the under-exploration of risk factors of intentional drowning deaths. This review identifies only age [52], gender [50], and substance use [90] as factors for suicidal drowning deaths, highlighting the lack of investigation in risk factors for fatal intentional drowning in Australia. A number of risk factors have been suggested by several studies as being important factors for suicide attempts, including: 1) socio-demographic characteristics, including age [13], gender [66, 91], socioeconomic status [92], unemployment [92, 93], rurality [94], and indigenous identification [95, 96]; 2) substance dependence [91]; 3) psycho-pathology, including depressive disorders [91, 93], psychotic disorders [91], neurotic disorders [91], and previous intentional self-harm attempts [9, 3336]; and 4) social dysfunction [91], including history of childhood abuse [97], social isolation [98], and homelessness [99]. A better understanding on the association of fatal intentional drowning and these risk factors, as illustrated in Fig 3, will also contribute to the development of public policy and the enhancement of community action in creating a supportive physical and social environment for mental health and intentional drowning prevention promotion in Australia. This conjunction of the enhancement of mental health promotion and deliberate self-harm prevention most likely differs from the development of unintentional drowning prevention strategies.

thumbnail
Fig 3. Risk factors of intentional drowning deaths needed to be investigated in future research.

https://doi.org/10.1371/journal.pone.0231861.g003

Strengths and limitations

This review has met its aims, including providing analysis on the rates, trends, and risk factors of intentional drowning in Australia, by performing a systematic literature review to identify original papers published between 2007 and 2017. This study has also shown the consistency of the source of data, with 80% of the articles identified in this study using the national-scale data from the ABS, AIHW, and NCIS. This identifies the potential utilisation of the national-scale data, with some improvements in the data collection system as discussed in the Recommendations for Future Research section, for further investigation of intentional drowning death in Australia. Similar proportions of suicide by drowning were also noted between the included studies with national-scale sources of data [48, 49, 55], with drowning identified as the preferred method of suicide in 2% to 3% from of all intentional self-harm deaths in Australia.

However, several major limitations were identified in this review. First of all, it is possible that not all studies exploring intentional drowning death in Australia were identified and included in this review. In addition, data collection and reporting between articles hinders the comparison of age-specific, gender-specific, intentional drowning rates between studies reviewed. Similarly, differences in the definition of intentional drowning may exist between studies, further complicating comparison.

It is also noted in this current study that although only observational studies were identified in the systematic search, different study designs may have affected the heterogeneity and the potential for reporting bias. Moreover, the exclusion of grey literature, including government reports, policy statements, issues papers, and theses, may also exclude other sources of data on intentional drowning in Australia. The current study also highlights the need for more up-to-date research on intentional drowning in Australia, with the bulk of the studies included in this review 10 years old or older. Furthermore, no studies identified in this current study investigated drowning deaths due to assault, highlighting the lack of peer-reviewed publications on homicidal drowning deaths in Australia and the need to further research on this topic in the future.

Conclusions

Limited publications reporting mortality rates and risk factors of intentional drowning deaths in Australia were identified in this review. A downward trend of suicidal drowning deaths was observed in Australia in one study, and in this study, being of older age groups was recognised as a risk factor of suicide drowning deaths in Australia. Psychoactive substances, particularly benzodiazepines and antidepressants, were identified amongst most suicidal drowning victims in the one study where this was investigated. This review identified suicide by drowning as the preferred method of suicide in only 2% to 3% of all intentional self-harm deaths in Australia. Improving death reporting systems and the legal framework for medico-legal death investigation, along with further research investigating the risk factors of intentional drowning, will inform the planning, implementation, and evaluation of prevention interventions for intentional drowning deaths in Australia.

Supporting information

S2 File. Data extraction table providing in-depth analysis of the included papers, including publication bias.

https://doi.org/10.1371/journal.pone.0231861.s002

(XLSX)

Acknowledgments

The authors thankfully acknowledge the College of Public Health, Medical and Veterinary Sciences, James Cook University, for providing a supportive research environment. The publication of this paper is supported by James Cook University, Australia.

References

  1. 1. Franklin R. C., Peden A. E., Hamilton E. B., Bisignano C., Castle C. D., Dingels Z. V., et al. (2020). The burden of unintentional drowning: global, regional and national estimates of mortality from the Global Burden of Disease 2017 Study. Injury Prevention, injuryprev-2019-043484. pmid:32079663
  2. 2. Ahlm K, Saveman B-I, Björnstig U. Drowning deaths in Sweden with emphasis on the presence of alcohol and drugs–a retrospective study, 1992–2009. BMC Public Health. 2013;13(1):216.
  3. 3. World Health Organization. Global health estimates 2015: Deaths by cause, age, sex, by country and by region, 2000–2015 2016 [Available from: http://www.who.int/healthinfo/global_burden_disease/estimates/en/index1.html.
  4. 4. World Health Organization. Violence and Injury Prevention–Drowning. World Health Organization 2019. [Available from: https://www.who.int/violence_injury_prevention/drowning/en/] Date accessed 31-10-2019.
  5. 5. Mitchell RJ, Williamson AM, Olivier J. Estimates of drowning morbidity and mortality adjusted for exposure to risk. Inj Prev. 2010;16(4):261–6. pmid:20696716
  6. 6. Peden AE, Franklin RC, Mahony AJ, Scarr J, Barnsley PD. Using a retrospective cross-sectional study to analyse unintentional fatal drowning in Australia: ICD-10 coding-based methodologies verses actual deaths. BMJ Open. 2017;7(12):e019407. pmid:29273670
  7. 7. Passmore JW, Ozanne-Smith J, Clapperton A. True burden of drowning: compiling data to meet the new definition. International Journal of Injury Control and Safety Promotion. 2007;14(1):1 pmid:17624004
  8. 8. Lunetta P, Smith GS, Penttilä A, Sajantila A. Unintentional drowning in Finland 1970–2000: A population-based study. Int J Epidemiol. 2004;33(5):1053–63. pmid:15218012
  9. 9. Ahlm K, Lindqvist P, Saveman B-I, Bjornstig U. Suicidal drowning deaths in northern Sweden 1992–2009—The role of mental disorder and intoxication. Journal of forensic and legal medicine. 2015;34:168–72. pmid:26165679
  10. 10. Cenderadewi M, Franklin RC, Peden AE, Devine S. Pattern of intentional drowning mortality: a total population retrospective cohort study in Australia, 2006–2014. BMC Public Health. 2019;19(1):207. pmid:30782167
  11. 11. Muccino E, Crudele GDL, Gentile G, Marchesi M, Rancati A, Zoja R. Suicide drowning in the non-coastal territory of Milan. Int J Legal Med. 2015;129(4):777–84. pmid:25398634
  12. 12. Puzo Q, Qin P, Mehlum L. Long-term trends of suicide by choice of method in Norway: A joinpoint regression analysis of data from 1969 to 2012. BMC Public Health. 2016;16(1):255.
  13. 13. Shah A, Buckley L. The current status of methods used by the elderly for suicides in England and Wales. Journal of Injury and Violence Research. 2011;3(2):68–73. pmid:21498968
  14. 14. Thomas KH, Beech E, Gunnell D. Changes in commonly used methods of suicide in England and Wales from 1901–1907 to 2001–2007. J Affect Disord. 2013;144(3):235–9. pmid:22871526
  15. 15. Fisher LB, Overholser JC, Dieter L. Methods of committing suicide among 2,347 people in Ohio. Death Stud. 2015;39(1–5):39–43. pmid:24932592
  16. 16. Kristóf I, Vörös K, Marcsa B, Váradi‐T A, Kosztya S, Törő K. Examination of the suicide characteristics based on the scene investigation in capital Budapest (2009–2011). Journal of Forensic Sciences. 2015;60(5):1229–33. pmid:26348224
  17. 17. Lee C-Y, Wu Y-W, Chen C-K, Wang L-J. The rate of fatality and demographic characteristics associated with various suicide methods: A community-based study in Northern Taiwan. Crisis. 2014;35(4):245–52. pmid:25113889
  18. 18. Matsuyama T, Kitamura T, Kiyohara K, Hayashida S, Kawamura T, Iwami T, et al. Characteristics and outcomes of emergency patients with self-inflicted injuries: A report from ambulance records in Osaka City, Japan. Scand J Trauma Resusc Emerg Med. 2016;24(1):68.
  19. 19. Oude Voshaar RC, Van Der Veen DC, Kapur N, Hunt I, Williams A, Pachana NA. Suicide in patients suffering from late-life anxiety disorders; A comparison with younger patients. Int Psychogeriatr. 2015;27(7):1197–205. pmid:25669916
  20. 20. Yoshioka E, Hanley SJ, Kawanishi Y, Saijo Y. Time trends in method-specific suicide rates in Japan, 1990–2011. Epidemiology and Psychiatric Sciences. 2016;25(1):58–68. pmid:25373686
  21. 21. Chattopadhyay S, Shee B, Sukul B. Unidentified bodies in autopsy–A disaster in disguise. Egyptian Journal of Forensic Sciences. 2013;3(4):112–5.
  22. 22. He S, Lunnen JC, Zia N, Khan U, Shamim K, Hyder AA. Pattern of presenting complaints recorded as near-drowning events in emergency departments: A national surveillance study from Pakistan. BMC Emerg Med. 2015;15 Suppl 2:S4.
  23. 23. Kitulwatte ID, Edirisinghe PAS. Study on unnatural childhood deaths presented to North Colombo Teaching Hospital, Sri Lanka. Med Sci Law. 2014;54(2):74–7. pmid:23966353
  24. 24. Kuchewar SV, Meshram RD, Gadge SJ, Khetre RR. Epidemiological study of drowning in Yavatmal. Medico—Legal Update. 2013;13(1):102–5.
  25. 25. Raghavendra Babu YP, Joseph N, Kadur K. Mortality among homeless and unclaimed bodies in Mangalore city—An insight. J Forensic Leg Med. 2012;19(6):321–3. pmid:22847048
  26. 26. Thakar MK, Guleria P. Tracking drowning trends in Himachal Pradesh during 2006–2010. Anil Aggrawal's Internet J Forensic Med Toxicol. 2015;16(1).
  27. 27. Hossain M, Mani KKC, Sidik SM, Hayati KS, Rahman AKMF. Socio-demographic, environmental and caring risk factors for childhood drowning deaths in Bangladesh. BMC Pediatr. 2015;15:114. pmid:26357879
  28. 28. Campbell LA, Jackson L, Bassett R, Bowes MJ, Donahue M, Cartwright J, et al. Can we use medical examiners' records for suicide surveillance and prevention research in Nova Scotia? Chronic Dis Inj Can. 2011;31(4):165–71. pmid:21978640
  29. 29. Chung C-H, Pai L, Kao S, Lee M-S, Yang T-T, Chien W-C. The interaction effect between low income and severe illness on the risk of death by suicide after self-harm. Crisis: The Journal of Crisis Intervention and Suicide Prevention. 2013;34(6):398–405.
  30. 30. World Health Organization. Public health action for the prevention of suicide: A framework. 2012.
  31. 31. Centers for Disease Control and Prevention. Ten leading causes of death by age group, United States- 2015: Centers for Disease Control and Prevention; [updated 2 May 2017. Available from: https://www.cdc.gov/injury/images/lc-charts/leading_causes_of_death_age_group_2015_1050w740h.gif.
  32. 32. Australian Bureau of Statistics. Causes of deaths, Australia, 2015: Australian Bureau of Statistics; 2016 [Available from: http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/3303.0~2015~Main%20Features~Intentional%20self-harm:%20key%20characteristics~8.
  33. 33. Hunt IM, Kapur N, Robinson J, Shaw J, Flynn S, Bailey H, et al. Suicide within 12 months of mental health service contact in different age and diagnostic groups: National clinical survey. The British Journal of Psychiatry. 2006;188(2):135–42.
  34. 34. Shah A, Ganesvaran T. Suicide among psychiatric in-patients with schizophrenia in an Australian mental hospital. Med Sci Law. 1999;39(3):251–9. pmid:10466321
  35. 35. Shah A, Ganesvaran T. Completed suicide among psychiatric in-patients with depression in an Australian mental hospital. Int J Methods Psychiatr Res. 2000;9(1):25–31.
  36. 36. Shah AK, Ganesvaran T. Inpatient suicides in an Australian mental hospital. Australian and New Zealand Journal of Psychiatry. 1997;31(2):291–8. pmid:9140639
  37. 37. Woo SH, Park JH, Choi SP, Wee JH. Comparison of clinical characteristics of intentional vs accidental drowning patients. The American Journal of Emergency Medicine. 2015;33(8):1062–5. pmid:25963676
  38. 38. Murray CJL, Vos T, Lozano R, Naghavi M, Flaxman AD, Michaud C, et al. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990–2010: A systematic analysis for the Global Burden of Disease Study 2010. The Lancet. 2012;380(9859):2197–223.
  39. 39. Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, Ezzati M, et al. Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990–2010: A systematic analysis for the Global Burden of Disease Study 2010. The Lancet. 2012;380(9859):2163–96.
  40. 40. Whiteford HA, Degenhardt L, Rehm J, Baxter AJ, Ferrari AJ, Erskine HE, et al. Global burden of disease attributable to mental and substance use disorders: Findings from the Global Burden of Disease Study 2010. The Lancet.382(9904):1575–86.
  41. 41. Pelling N. Mental health in Australia. Int J Ment Health. 2015;44(1–2):1–3.
  42. 42. McKay K, Tighe J. Talking through the Dead: The Impact and Interplay of Lived Grief after Suicide. OMEGA—Journal of Death and Dying. 2014;68(2):111–21.
  43. 43. Sanford R, Cerel J, McGann V, Maple M. Suicide loss survivors′ experiences with therapy: Implications for clinical practice. Community Ment Health J. 2016;52(5):551–8. pmid:27074845
  44. 44. Ljung T, Sandin S, Långström N, Runeson B, Lichtenstein P, Larsson H. Offspring death and subsequent psychiatric morbidity in bereaved parents: Addressing mechanisms in a total population cohort. Psychol Med. 2014;44(9):1879–87. pmid:24176129
  45. 45. Seeman MV. The impact of suicide on co-patients. Psychiatr Q. 2015;86(4):449–57. pmid:25618004
  46. 46. Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. BMJ. 2009;339(7716):332–6.
  47. 47. Ciliska D, Thomas H, Buffett C. A compendium of critical appraisal tools for public health practice2008. Available from: http://homepages.ulb.ac.be/~aleveque/epitraumac/pdf-ppt/eiph_backgrounder.pdf.
  48. 48. Byard R, Austin AE, Van Den Heuval C. Suicide in forensic practice-An Australian perspective. Aust J Forensic Sci. 2011;43(1):65–76.
  49. 49. Darke S, Duflou J, Torok M. Toxicology and circumstances of completed suicide by means other than overdose. J Forensic Sci. 2009;54(2):490–4. pmid:19220656
  50. 50. Donaldson S, Bi P, Hiller JE. Secular change in mortality from suicide in Australia during the 20th century. Aust J Prim Health. 2007;13(1):45–51.
  51. 51. Dyson K, Morgans A, Bray J, Matthews B, Smith K. Drowning related out-of-hospital cardiac arrests: Characteristics and outcomes. Resuscitation. 2013;84(8):1114–8. pmid:23370162
  52. 52. Koo YW, Kõlves K, De Leo D. Suicide in older adults: Differences between the young-old, middle-old, and oldest old. Int Psychogeriatr. 2017;29(8):1297–306. pmid:28511737
  53. 53. Milner A, Witt K, Maheen H, LaMontagne A. Access to means of suicide, occupation and the risk of suicide: A national study over 12 years of coronial data. BMC Psychiatry. 2017;17(1):125. pmid:28376757
  54. 54. Pirkis J, Burgess P, Blood RW, Francis C. The newsworthiness of suicide. Suicide Life-Threat Behav. 2007;37(3):278–83. pmid:17579540
  55. 55. Robinson J, Too LS, Pirkis J, Spittal MJ. Spatial suicide clusters in Australia between 2010 and 2012: A comparison of cluster and non-cluster among young people and adults. BMC Psychiatry. 2016;16(1):417. pmid:27876026
  56. 56. Sveticic J, Too LS, De Leo D. Suicides by persons reported as missing prior to death: A retrospective cohort study. BMJ Open. 2012;2(2).
  57. 57. Walter SJ, Bugeja L, Spittal MJ, Studdert DM. Factors predicting coroners' decisions to hold discretionary inquests. CMAJ. 2012;184(5):521–8. pmid:22291169
  58. 58. Milner A, Maheen H, Currier D, LaMontagne AD. Male suicide among construction workers in Australia: A qualitative analysis of the major stressors precipitating death. BMC Public Health. 2017;17(1):584. pmid:28629352
  59. 59. Alexander D. A comparison of suicide predictors between African Americans and Caucasians. ProQuest Dissertations Publishing. 2010;AAI3368234:1–5148.
  60. 60. Saman DM, Walsh S, Borówko A, Odoi A. Does place of residence affect risk of suicide? A spatial epidemiologic investigation in Kentucky from 1999 to 2008. BMC Public Health. 2012;12(1):108.
  61. 61. Purandare N, Voshaar RCO, Rodway C, Bickliey H, Burns A, Kapur N. Suicide in dementia: 9-year national clinical survey in England and Wales. The British Journal of Psychiatry. 2009;194(2):175–80. pmid:19182182
  62. 62. Chang S-S, Sterne JAC, Lu T-H, Gunnell D. ‘Hidden’ suicides amongst deaths certified as undetermined intent, accident by pesticide poisoning and accident by suffocation in Taiwan. Social Psychiatry and Psychiatric Epidemiology. 2010;45(2):143–52. pmid:19363577
  63. 63. Ajdacic-Gross V, Tran US, Bopp M, Sonneck G, Niederkrotenthaler T, Kapusta ND, et al. Understanding weekly cycles in suicide: An analysis of Austrian and Swiss data over 40 years. Epidemiology and Psychiatric Sciences. 2015;24(4):315–21. pmid:24759304
  64. 64. Hepp U, Ring M, Frei A, Rössler W, Schnyder U, Ajdacic-Gross V. Suicide trends diverge by method: Swiss suicide rates 1969–2005. Eur Psychiatry. 2010;25(3):129–35. pmid:19695842
  65. 65. Perret G, Abudureheman A, Perret-Catipovic M, Flomenbaum M, La Harpe R. Suicides in the young people of Geneva, Switzerland, from 1993 to 2002. J Forensic Sci. 2006;51(5):1169–73. pmid:17018104
  66. 66. Värnik A, Kõlves K, van der Feltz-Cornelis CM, Marusi A, Oskarsson H, Palmer A, et al. Suicide methods in Europe: A gender-specific analysis of countries participating in the "European Alliance against Depression.". J Epidemiol Community Health. 2008;62(6):545–51. pmid:18477754
  67. 67. Niederkrotenthaler T, Till B, Herberth A, Voracek M, Kapusta ND, Etzersdorfer E, et al. The gap between suicide characteristics in the print media and in the population. Eur J Public Health. 2009;19(4):361–4. pmid:19304730
  68. 68. Putkonen H, Amon S, Eronen M, Klier CM, Almiron MP, Cederwall JY, et al. Gender differences in filicide offense characteristics—A comprehensive register-based study of child murder in two European countries. Child Abuse Negl. 2011;35(5):319–28. pmid:21620158
  69. 69. Baumert J, Erazo N, Ruf E, Ladwig K-H. Time trends in suicide mortality vary in choice of methods: An analysis of 145,865 fatal suicide cases in Germany 1991–2002. Soc Psychiatry Psychiatr Epidemiol. 2008;43(11):913–9. pmid:18560783
  70. 70. Mock C, Quansah R, Krishnan R, Arreola-Risa C, Rivara F. Strengthening the prevention and care of injuries worldwide. The Lancet. 2004;363(9427):2172–9.
  71. 71. Vijayakumar L, Armstrong G. Surveillance for self-harm: an urgent need in low-income and middle-income countries. The Lancet Psychiatry. 2019;6(8):633–4. pmid:31272911
  72. 72. Lundholm L, Thiblin I, Runeson B, Leifman A, Fugelstad A. Acute influence of alcohol, THC or central stimulants on violent suicide: A Swedish population study. J Forensic Sci. 2014;59(2):436–40. pmid:24745078
  73. 73. Stemberga V, Bralic M, Coklo M, Cuculic D, Bosnar A. Suicidal drowning in Southwestern Croatia: A 25-year review. The American journal of forensic medicine and pathology. 2010;31(1):52–4. pmid:19918158
  74. 74. Franklin RC, Scarr JP, Pearn JH. Reducing drowning deaths: the continued challenge of immersion fatalities in Australia. Med J Aust. 2010;192(3):123. pmid:20121677
  75. 75. Peden AE, Franklin RC, Leggat PA. The hidden tragedy of rivers: A decade of unintentional fatal drowning in australia. PLoS One. 2016;11(8):e0160709. pmid:27517313
  76. 76. Islam MM, Conigrave KM, Day CA, Nguyen Y, Haber PS. Twenty-year trends in benzodiazepine dispensing in the Australian population. Intern Med J. 2014;44(1):57–64. pmid:24450521
  77. 77. Brett J, Murnion B. Management of benzodiazepine misuse and dependence. Australian Prescriber. 2015;38(5):152–5. pmid:26648651
  78. 78. Reynolds M, Fulde G, Hendry T. Trends in benzodiazepine abuse: 2007–2011. Emerg Med Australas. 2013;25(2):199–200.
  79. 79. Andrea Mant VARWDHPBMWSMPRMIBH. Making new choices about antidepressants in Australia: the long view 1975–2002. Med J Aust. 2004;181(7):S21–4.
  80. 80. Brijnath B, Xia T, Turner L, Mazza D. Trends in GP prescribing of psychotropic medications among young patients aged 16–24 years: a case study analysis. BMC Psychiatry. 2017;17.
  81. 81. Sawyer MG, Reece CE, Sawyer AC, Johnson S, Lawrence D, Zubrick SR. The prevalence of stimulant and antidepressant use by australian children and adolescents with attention-deficit/hyperactivity disorder and major depressive disorder: A national survey. J Child Adolesc Psychopharmacol. 2017;27(2):177–84. pmid:27154239
  82. 82. Höfer P, Rockett IRH, Värnik P, Etzersdorfer E, Kapusta ND. Forty years of increasing suicide mortality in Poland: Undercounting amidst a hanging epidemic? BMC Public Health. 2012;12(1):644.
  83. 83. Lin C-Y, Wang Y-F, Lu T-H, Kawach I. Unintentional drowning mortality, by age and body of water: An analysis of 60 countries. Injury prevention: journal of the International Society for Child and Adolescent Injury Prevention. 2015;21(e1):e43–50.
  84. 84. Lu T-H, Lunetta P, Walker S. Quality of cause-of-death reporting using ICD-10 drowning codes: a descriptive study of 69 countries. BMC Medical Research Methodology. 2010;10(1):30.
  85. 85. Bhalla K, Harrison JE, Fingerhut LA, Shahraz S, Abraham J, Yeh P-H, et al. The global injury mortality data collection of the Global Burden of Disease Injury Expert Group: A publicly accessible research tool. International Journal of Injury Control and Safety Promotion. 2011;18(3):249–53. pmid:21506037
  86. 86. Bakst SS, Braun T, Zucker I, Amitai Z, Shohat T. The accuracy of suicide statistics: Are true suicide deaths misclassified? Social Psychiatry and Psychiatric Epidemiology. 2016;51(1):115–23. pmid:26364837
  87. 87. Chan CH, Caine ED, Chang SS, Lee WJ, Cha ES, Yip PSF. The Impact of improving suicide death classification in South Korea: A Comparison with Japan and Hong Kong. PLOS ONE. 2015;10(5):e0125730. pmid:25992879
  88. 88. Bohnert ASB, McCarthy JF, Ignacio RV, Ilgen MA, Eisenberg A, Blow FC. Misclassification of suicide deaths: Examining the psychiatric history of overdose decedents. Injury Prevention. 2013;19(5):326. pmid:23322257
  89. 89. Tøllefsen IM, Helweg-Larsen K, Thiblin I, Hem E, Kastrup MC, Nyberg U, et al. Are suicide deaths under-reported? Nationwide re-evaluations of 1800 deaths in Scandinavia. BMJ Open. 2015;5(11).
  90. 90. Tsirigotis K, Gruszczynski W, Tsirigotis M. Gender differentiation in methods of suicide attempts. Medical Science Monitor: International Medical Journal of Experimental and Clinical Research. 2011;17(8):PH65–PH70.
  91. 91. Park S, Ahn MH, Na R, Kim S-O, Yoon JS, Park J-H, et al. Factors associated with suicide method among psychiatric patients in a general hospital in Korea. Psychiatry Research. 2013;210(3):945–50. pmid:24055162
  92. 92. Kim JL, Kim JM, Choi Y, Lee T-H, Park E-C. Effect of socioeconomic status on the linkage between suicidal ideation and suicide attempts. Suicide Life-Threat Behav. 2016;46(5):588–97. pmid:26991513
  93. 93. Moga M, Burtea V, Ifteni P. Socioeconomic status and psychological factors involved in suicide. Revista De Cercetare Si Interventie Sociala. 2014;45:230–9.
  94. 94. Santana P, Costa C, Cardoso G, Loureiro A, Ferrão J. Suicide in Portugal: Spatial determinants in a context of economic crisis. Health & Place. 2015;35(Supplement C):85–94.
  95. 95. Webster PC. Canada's Indigenous suicide crisis. The Lancet. 2016;387(10037):2494.
  96. 96. Campbell A, Chapman M, McHugh C, Sng A, Balaratnasingam S. Rising Indigenous suicide rates in Kimberley and implications for suicide prevention. Australasian Psychiatry. 2016;24(6):561–4. pmid:27634840
  97. 97. Martin MS, Dykxhoorn J, Afifi TO, Colman I. Child abuse and the prevalence of suicide attempts among those reporting suicide ideation. Social Psychiatry and Psychiatric Epidemiology. 2016;51(11):1477–84. pmid:27290608
  98. 98. Ahmadpanah M, Astinsadaf S, Akhondi A, Haghighi M, Sadeghi Bahmani D, Nazaribadie M, et al. Early maladaptive schemas of emotional deprivation, social isolation, shame and abandonment are related to a history of suicide attempts among patients with major depressive disorders. Comprehensive Psychiatry. 2017;77(Supplement C):71–9.
  99. 99. Calvo-García F, Giralt-Vázquez C, Calvet-Roura A, Carbonells-Sánchez X. Suicide risk among homeless population. Clínica y Salud. 2016;27(2):89–96.