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Childhood injuries
Drowning and near-drowning in Northern Territory childrenKaren M Edmond, John R Attia, Catherine A D'Este and John T Condon
MJA 2001; 175: 605-608
For editorial comment, see Pitt and Cass
Abstract -
Methods -
Results -
Discussion -
Acknowledgements -
Competing interests -
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More articles on Paediatrics
Abstract |
Objective: To compare incidences of drowing for
children in the Northern Territory (NT) with those in Queensland and
the rest of Australia. Design: Descriptive, retrospective, population-based analysis of death and hospitalisation data for drowning and near-drowning. Setting and participants: Children aged 0-14 years resident in Australia from 1983 to 1998. Main outcome measures: Age-standardised average annual incidence of drowning (1983-1998) and near-drowning (1994-1997) in children aged 0-4 and 5-14 years in the NT, Queensland and the rest of Australia. Results: The average annual incidence of drowning and near-drowning from 1994 to 1997 for children aged 0-4 years in the NT (67.82 per 100 000) was significantly higher than for Australia (24.45 per 100 000) (incident rate ratio [IRR], 2.77; 95% CI, 1.40-4.91) and for Queensland (32.55 per 100 000) (IRR, 2.13; 95% CI, 1.05-3.94). The proportion of children aged 0-4 years drowning or near-drowning in swimming pools from 1994 to 1997 was also significantly higher in the NT (83%) than Australia (64%) (difference, 0.19; 95% CI, 0.086-0.30) and Queensland (65%) (difference, 0.18; 95% CI, 0.069-0.29). From 1983 to 1998, the incidence of drowning in NT children aged 0-4 years increased by 0.4% per year (IRR, 1.004; 95% CI, 0.994-1.070), compared with a 5.0% reduction per year (IRR, 0.950; 95% CI, 0.937-0.963) in Australian children. Conclusions: The incidences of drowning and near-drowning in the NT are higher than in the rest of Australia and show no significant decrease. The NT should improve its measures for prevention of childhood drowning. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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In Australia, childhood drownings are second only to road trauma as a
cause of injury death in children younger than 15 years.1,2
Encouragingly, the overall incidence of
childhood drowning in Australia appears to be
decreasing.1,3
However, drowning death rates are higher in the
Northern Territory (NT) than the rest of Australia.1,4-6 There is
also some evidence that rates of drowning in the NT are not decreasing
as fast as those in the rest of Australia.4,5 However, there are no
published studies that compare rates of near-drowning in the NT with
rates in the rest of Australia. There are also no published analyses of
NT drowning trends.
Risk groups for drowning include children aged 0-4 years,1,3 children living in cities with high swimming pool to population ratios,7-10 children living in hot climates,3,8 children living in areas with lack of isolation pool fencing,11-14 and Indigenous children.4,5,7 However, there are no published NT data concerning these risk groups. The proportion of NT children drowning in swimming pools is also currently unknown. This study was designed to determine how incidences of childhood drowning and near-drowning in the NT compare with rates in the rest of Australia and in Queensland (another State with a similar climate and similar numbers of domestic swimming pools per capita as the NT). We aimed to stratify our analysis according to specific risk groups (children aged 0-4 years, children aged 5-14 years, children drowning in swimming pools, and Indigenous children). We also planned to compare the proportion of NT children aged 0-4 years who drowned or nearly drowned in swimming pools with Queensland and the rest of Australia. The study was designed as a descriptive, retrospective, population-based analysis of hospital morbidity and mortality data for drowning and near-drowning, identified by International classification of diseases, 9th revision, clinical modification (ICD-9-CM) codes15 in children aged 0-14 years. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Methods | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Definitions | A drowning incident was defined as a non-intentional episode in which immersion of a child in water was followed by death. A near-drowning incident was defined as a non-intentional episode in which immersion of a child in water was followed by admission into hospital and the child subsequently surviving. A case was only included as a drowning or near-drowning if it was identified by specific ICD-9-CM external (E) cause codes (830, 832, 919.0-910.9) or the ICD-9-CM disease code for near-drowning (994.1).15 E-codes classify environmental sites, events, circumstances, and conditions as the cause of injury, and include a code for swimming pool drowning.15 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Data collection | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mortality and hospital morbidity data for all cases of drowning and near-drowning were obtained from the Australian Institute of Health and Welfare (AIHW). Mortality data were available for 1983-1998, but hospital morbidity near-drowning data were available for 1994-1997 only, because of the introduction of casemix funding and changes in ICD-9-CM coding.16 Population denominators for the NT, Queensland and the rest of Australia were the estimated resident population data for each year published by the Australian Bureau of Statistics (ABS).17 NT Indigenous population data were the estimates of the NT Indigenous population published by the ABS.18 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Data analysis |
Crude incidences of drowning and near-drowning for the NT,
Queensland and the rest of Australia were standardised year by year
within 0-4 and 5-14 years age groups using the indirect
standardisation method and the Australian population as the
reference population.19
The annual number of cases was assumed to follow a Poisson distribution.20 Changes in annual drowning death rates from 1983 to 1998 were investigated using the Mantel test for trend and a Poisson regression model which included terms for year. NT average annual incidences of age-standardised drowning and near-drowning were compared with Queensland and the rest of Australia using incident rate ratios (IRR) and 95% confidence intervals. An IRR was defined as the ratio of two incidences. The difference between proportions of children drowning or nearly drowning in swimming pools in the NT, Queensland and the rest of Australia was compared using tests of difference between two proportions and 95% confidence intervals. Stata software was used for statistical analysis.21 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Ethical approval | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| This study was approved by the Joint Institutional Ethics Committee of the Royal Darwin Hospital and the Menzies School of Health Research. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Results | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Drowning | Forty-two NT children drowned from 1983 to 1998. There was no significant change in the incidence of drowning over this period in NT children aged 0-4 or 5-14 years (Boxes 1 and 2). In contrast, rates of drowning in Australian children reduced significantly each year in children aged 0-4 years (Boxes 1A and 2). Rates in Australian children aged 5-14 years also reduced each year, but the Poisson regression rate ratio for trend per year did not reach statistical significance (Boxes 1B and 2). The average annual incidence of drowning in NT, Australian and Queensland children from 1994 to 1997 is shown in Box 3. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Near-drowning | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The NT incidence of near-drowning for children aged 0-4 years was higher than the Queensland rate, but not statistically significant, while the rate for children aged 5-14 years was similar to the Queensland rate (Box 3). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Swimming pool drowning and near-drowning | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The proportion of children aged 0-4 years drowning or near-drowning in swimming pools from 1994 to 1997 in the NT (83%) was higher than in Queensland (65%) (difference, 0.18; 95% CI, 0.069-0.29) and the rest of Australia (64%) (difference, 0.19; 95% CI, 0.086-0.30) (see Box 3 for incidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Indigenous status | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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In the NT, non-Indigenous children aged 0-4 years had higher rates of
drowning and near-drowning (73.19 per 100 000) than Indigenous
children (56.63 per 100 000) (IRR, 1.29; 95% CI, 0.53-4.47), although
this was not significant. Non-Indigenous children aged 5-14 years
also had higher rates of drowning and near-drowning (7.27 per 100 000)
than Indigenous children (5.41 per 100 000; IRR, 1.34; 95% CI,
0.81-5.42).
Rates of swimming pool drowning in the NT were also higher in non-Indigenous children aged 0-4 years (24.89 per 100 000) than Indigenous children (14.04 per 100 000) but this difference was not significant (IRR, 1.77; 95% CI, 0.91-6.22). Only five of 40 children (13%) aged 0-4 years who drowned in a swimming pool in the NT from 1983 to 1998 were Indigenous. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Discussion |
This study describes the extremely high incidence of drowning and
near-drowning in children in the NT. Incidences were higher than in
the rest of Australia and showed no significant decrease despite
reductions in the rest of Australia. Rates in the NT are among the
highest recorded worldwide.3-5
Indigenous children in the NT had lower rates of drowning and near-drowning than non-Indigenous children, as well as lower rates of swimming pool drowning, although the differences were not statistically significant. Case numbers of fresh water drownings were too small to allow statistical analysis. Some studies describe rates of drowning and near-drowning in Native American children to be two to three times those of non-Native American children.7,10 However, Australian studies report rates of Indigenous child drowning mortality similar to those reported here.4,5 Reporting of Indigenous status in the NT is accurate, in contrast to other Australian States and Territories.1 Near-drowning urban and rural hospital referral patterns are similar and are unlikely to have contributed to the difference in Indigenous and non-Indigenous rates. Reduced exposure of Indigenous children to domestic swimming pools is a possible explanation. Further prospective research is required to clarify these issues. There are many reports of the high rates of drowning in children aged 0-4 years.1,2,9,11 In our study, children aged 0-4 years in the NT, Queensland and the rest of Australia had rates of drowning and near-drowning 5-10 times higher than children aged 5-14 years. Young children in the NT appeared to be at greatest risk, with rates of drowning and near-drowning nearly three times higher than the rest of Australia and Queensland. Rates of swimming pool drowning in children aged 0-4 years in the NT were more than twice the Australian and Queensland rates and among the highest in the world.2,8,9,11 The proportion of children drowning in swimming pools in the NT was also statistically higher than in Queensland and the rest of Australia. Drowning rescue and resuscitation protocols in the NT are similar to those in the rest of Australia. One possible explanation for the differences between NT and Queensland rates of swimming pool drowning is that Queensland introduced statewide pool fencing legislation in 1992, while pool fencing laws in the NT are still inadequate. All the NT swimming pool drowning deaths reported in this study occurred in pools with non-Australian Standards fencing (NT coroner, personal communication). There is no standard legislation for pool fencing in the NT. Only one jurisdiction (encompassing less than 10% of the population) requires fencing according to Australian Standards. Other reasons for the disparity between NT and Queensland rates of drowning could be differences in exposure to water, differences in exposure to swimming pools, or differences in parental supervision. Further prospective research is needed to investigate the role of these different risk factors. We may have underestimated rates of drowning and near-drowning, as retrospective data were used and case ascertainment relied on coded cause of death/hospitalisation. We may also have under-reported NT rates of near-drowning, as the ratio of near-drowning to drowning in the NT (2:1) was lower than Australia (9:1) and Queensland (9:1). Smaller numbers of NT drowning and near-drowning cases also produced considerable variation in annual NT data. However, statistical analyses, including Poisson regression, enabled analysis of trend over time. In response to this study and other reports, NT injury prevention groups are planning to expand their drowning prevention campaigns. This will include lobbying the NT government to enact isolation/four-sided pool-fencing legislation. More public awareness campaigns are also planned. These will be directed towards the need for effective pool fencing, parental supervision of young children, and cardiopulmonary resuscitation skills, and will include other measures that can assist in preventing drowning in young children. Kidsafe NT also intends to use the information from this study to develop a prospective drowning surveillance system. This system will be used to evaluate drowning prevention interventions and to further investigate NT risk factors for childhood drowning, including the role of swimming pool fencing.
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Acknowledgements | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Kidsafe, Child Accident Prevention Foundation of Australia, NT branch, provided the funding for the data extraction by the Australian Institute of Health and Welfare. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Competing interests | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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None declared. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
References |
(Received 23 Feb, accepted 30 Jul, 2001) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Territory Health Services, Casuarina, NT.
Karen M Edmond, FRACP, MMedSc (ClinEpid), Community Paediatrician.
Centre for Epidemiology and Biostatistics, University of
Newcastle, Newcastle, NSW.
Menzies School of Health Research, Casuarina, NT.
Reprints will not be available from the authors. ©MJA 2001
Readers may print a single copy for personal use. No further reproduction or distribution of the articles should proceed without the permission of the publisher. For permission, contact the Australasian Medical Publishing Company. Journalists are welcome to write news stories based on what they read here, but should acknowledge their source as "an article published on the Internet by The Medical Journal of Australia <http://www.mja.com.au>". <URL: http://www.mja.com.au/> © 2001 Medical Journal of Australia. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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2
(degrees per year of freedom)