J Immigrant Minority Health DOI 10.1007/s10903-014-0095-7
ORIGINAL PAPER
Ethnic Differences in Drowning Rates in Ontario, Canada Zane R. Gallinger • Michael Fralick Stephen W. Hwang
•
Ó Springer Science+Business Media New York 2014
Abstract The scientific literature suggests ethnicity may be a risk factor for drowning. Ontario, Canada is one of the most ethnically diverse places in the world. The objective of our study was to determine if Asians, Africans and Hispanics were at an increased risk of drowning compared to Greater Europeans. Ethnicity served as a surrogate for country of origin. Using Coroner’s reports, all unintentional drowning deaths in Ontario from 2004 to 2008 were reviewed. The ethnicity of drowning victims was estimated using a previously validated name-based ethnicity classifier. Age-standardized drowning rates were calculated by sex and place of residence (rural vs. non-rural) for people of each ethnicity group using the method of direct standardization. For residents of Ontario living in rural areas, the age-standardized drowning rate was significantly higher among men of Asian, African, or Hispanic ethnicity compared to men of Greater European ethnicity (RR 13.9; 95 % CI 8.1–23.8) and for women of Asian, African, or Hispanic ethnicity compared to women of Greater European ethnicity (RR 23.9; 95 % CI 6.4–89.1). These highrisk individuals need to be considered when developing drowning prevention strategies. Z. R. Gallinger M. Fralick Internal Medicine Residents, Faculty of Medicine, University of Toronto, Toronto, Canada e-mail: [email protected] S. W. Hwang (&) Centre for Research on Inner City Health, The Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, 30 Bond St., Toronto, ON M5B 1W8, Canada e-mail: [email protected] S. W. Hwang Division of General Internal Medicine, Department of Medicine, University of Toronto, Toronto, Canada
Keywords Drowning Ethnicity Ontario Harm prevention Swimming Immigrant
Introduction Drowning is the second leading cause of unintentional injury death worldwide, after motor vehicle injuries [1]. In Ontario, Canada’s largest province, approximately 150 drownings occur each year, representing a serious health concern [2]. In 2004, drowning deaths and hospitalizations for drownings and near-drownings in Ontario resulted in approximately 33 million dollars in direct and indirect costs [3]. The Canadian Lifesaving Society and the Canadian Red Cross promote drowning prevention programs for the general public, but it is unclear if specific populations require increased efforts or targeted interventions for drowning prevention. Approximately 28 % of Ontarians, or 3.4 million people, are immigrants who were born outside of Canada, making Ontario one of the most diverse places in the world [4]. Recent census data indicate that Ontario’s citizens represent over 200 different ethnicities [5]. Furthermore, the majority (65 %) of newcomers to Canada are from developing nations within Asia where swimming skills are not routinely taught [4]. Despite Ontario’s ethnic diversity, we are unaware of any studies examining the ethnicity of drowning victims in Ontario. Studies in the United States and the Netherlands have found a higher risk of drowning among certain ethnic groups, possibly related to a lack of swimming and water safety skills [6, 7]. In addition, specific cultural beliefs as well as a lack of familiarity and exposure to swimming environment may play a role in how individuals approach aquatic environments [8].
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The objective of this study was to determine if certain ethnic groups in Ontario are at increased risk of drowning. Because both the risk of drowning and the proportion of individuals belonging to different ethnicities were expected to vary widely in rural compared to non-rural areas, we conducted separate analyses of drowning rates in rural and non-rural areas of Ontario.
Methods Study Setting Ontario is the largest province in Canada by population (13.6 million) and second largest by land mass (1 million km2). Ontario has over 250,000 freshwater lakes, four of which make up the Great Lakes Basin, which is the largest continuous body of fresh water in the world. Over 98 % of Ontario residents live within the Great Lakes Basin. According to the 2006 Canadian Census, there were approximately 2,745,200 visible minorities living in Ontario (54 % of Canada’s total visible minority population) [4]. Approximately 23 % of Ontario residents identify themselves as visible minorities, with the three largest groups being South Asian, Chinese, and Black [5]. About 41 % of Ontario residents report being of British Isles origins, and 36 % report being of other European origins [5]. Drowning Case Identification Data related to drowning deaths in Ontario, Canada, were obtained from the Office of the Chief Coroner, which investigates all drowning deaths in the province. Unintentional drowning deaths occurring during the 5-year period from January 1, 2004, through December 31, 2008, were eligible for inclusion in the study. At the time of the study, the 2006 Canadian census was the most recent available. The 5-year period 2004–2008 was selected to be centered around this year. Drowning deaths were excluded if the victim was not a resident of Ontario or if the victim did not have a residential postal code recorded in the Coroner’s database. Drowning deaths that occurred in a bathtub were excluded because they were not plausibly related to swimming ability or water safety skills. Intentional drowning deaths, as determined by the Coroner to be due to suicide or homicide, were also excluded. Demographic Information Demographic information, including each drowning victim’s age, sex, and residential postal code, were obtained from the Office of the Chief Coroner. When the Coroner
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attends the scene of a drowning, the postal code of the drowning victim is collected from the victim’s driver’s license or another available form of identification. Age was grouped into the following categories: 0–4, 5–14, 15–24, 25–34, 35–44, 45–54, 55–64, 65–74, and 75? years. Medical comorbidities, autopsy findings, and toxicology results were also obtained from the Coroner’s records (Table 1). Toxicology testing is routinely ordered on all drowning victims. Residential postal codes were used to classify decedents as residents of rural or non-rural areas of Ontario. This process used a previously validated algorithm, the Postal Code Conversion File Plus (PCCF?) [9]. Each postal code was mapped to a rural area, or to a Census Metropolitan Area (CMA), which is by definition a non-rural area. Ethnicity Classification Since the Office of the Chief Coroner does not obtain information on the ethnicity or country of birth of decedents, the following procedures were used to impute the ethnicity of drowning victims. The names of drowning victims were entered into a validated name-ethnicity classification program [10]. The name-ethnicity classification reported precision statistics (Table 2), which are comparable with most ethnicity classification systems [10]. This computerized classification algorithm identifies probable ethnicity based on first and last name. The algorithm classifies individuals into one of three primary ethnic categories (Asian, Greater African, or Greater European) and an ethnic subcategory within each of these primary categories (Fig. 1). These ethnicities were chosen by the researchers who developed the classification algorithm because their model determined they had the highest accuracy and precisions. These name-based ethnic categories were then converted to corresponding ethnic groups used by Statistics Canada in the 2006 Census (Table 3). The number of drowning deaths was tabulated by sex, age group, place of residence (rural vs. non-rural), and ethnic group (Asian, Greater African, Hispanic, and Greater European). Since the number of drowning victims within each ethnic subgroup of Asian, African, and Hispanic were relatively small, these groups were combined and analyzed as a single group. Ethnicity was used as a surrogate marker for country of origin. Of note, the ethnicity classifier included Hispanic in the Greater European group; however, we included these individuals in our nonGreater European group. Our focus was on identifying individuals of Asian, Greater African, and Hispanic decent, who together account for the vast majority of visible minorities in Ontario [5]. According to the 2006 Census, over 75 % of visible minorities were born outside of Canada [5].
J Immigrant Minority Health Table 1 Characteristics of unintentional drowning victims in Ontario, 2004–2008, by ethnicity (n = 492)
Characteristic
Asian, African or Hispanic ethnicity N (%)
Greater European ethnicity
N (%)
Male
87 (86)
347 (89)
Female Age group
14 (14)
44 (11)
0–4
3 (3)
13 (3)
5–14
12 (12)
18 (5)
15–24
21 (21)
64 (16)
25–34
19 (19)
50 (13)
35–44
11 (11)
57 (15)
45–54
18 (18)
61 (16)
55–64
6 (6)
56 (14)
65–74
5 (5)
32 (8)
75?
6 (6)
40 (10)
Non-rural
82 (81)
274 (70)
Rural
19 (19)
117 (30)
Greater European (other than Hispanic) Asian
– 43 (43)
391 (100) –
Greater African
34 (34)
–
Hispanic
24 (23)
–
Open water
79 (78)
337 (86)
Public pool
6 (6)
8 (2)
Private pool
15 (15)
30 (8)
1 (1)
13 (3)
Sex
0.58
0.02
Place of residence
0.04
Ethnicitya
n/a
Setting of drowningb a
See text for details on methods used to impute ethnicity
b
Drownings occurring in bathtubs were excluded
c
Comorbid conditions that were deemed to potentially contribute to drowning were diabetes, epilepsy, cerebrovascular accident, psychiatric conditions, trauma, acute drug intoxication, respiratory diseases, and myocardial infarction
Pond/quarry/casual water Unspecified/other
p value
0.02
(0)
3 (1)
Absence of personal flotation device
20 (20)
66 (17)
0.59
Alcohol use as contributing factor
24 (24)
138 (35)
0.03
None
76 (75)
283 (72)
One present
21 (21)
85 (22)
4 (4)
23 (6)
Comorbid conditionsc
Two or more present
Ethics Statement The names of drowning victims were entered into the ethnicity classification program at the Office of the Coroner, which is a secure, locked facility. To protect the confidentiality of decedents and their families, only the ethnicity of decedents and not their names were recorded in the study database. After the postal code of decedents was used to determine rural versus non-rural place of residence, the postal code was deleted from the database. This study
0.72
was approved by the St. Michael’s Hospital Research Ethics Board. Statistical Analysis Characteristics of drowning victims of Greater European (group 1) and the combined group of Asian, Greater African, and Hispanic ethnicities (group 2) were compared using the Chi square test. Statistical significance was defined as a p value less than 0.05.
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J Immigrant Minority Health Table 2 Name-based ethnic categories from ethnicity classifier and corresponding precision, recall, and F-score [10]
Table 3 Name-based ethnic categories and corresponding census ethnic groups used to classify individuals
Name-based ethnic categories
Precision
Recall
F-score
Name-based ethnic categories
Census ethnic groups
Asian
0.82
0.83
0.82
Asian
West Asian, South Asian, East Asian, and Southeast Asian
Hispanic
0.68
0.62
0.65
Greater African
0.56
0.75
0.65
Greater African
African
0.95
Hispanic Greater European (other than Hispanic)
Hispanic All other ethnic groups
Greater European
0.96
0.93
Data on the total population of Ontario, stratified by sex, age group, place of residence (rural vs. non-rural), and ethnicity, were obtained from the 2006 Canadian Census. Of 144 sex-, age group-, place of residence- and ethnicityspecific groups, the population estimates for 16 groups were suppressed by Statistics Canada due to low counts in the census sample used to generate the population estimate. The population in each of these groups was estimated by taking the mean of the adjacent age groups within the same sex-, place of residence-, and ethnicity-specific stratum. Drowning rates for each ethnicity grouping were calculated by sex, age group, and place of residence. Rates were expressed as deaths per 100,000 person-years. Rates ratios comparing drowning rates between group 1 and group 2 were calculated by sex, age group, and place of residence. Fig. 1 Name-based ethnic categories used for ethnicity classification [10]
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Age-standardized drowning rates were calculated for group 2 using the method of direct standardization, with group 1 serving as the standard population. Standardized rate ratios comparing drowning rates among people of group 1 and group 2 were calculated by sex and place of residence.
Results Drowning Cases Between 2004 and 2008, a total of 492 Ontario residents died of unintentional drowning and met study inclusion
J Immigrant Minority Health Table 4 Drowning rates (deaths per 100,000 person-years) among persons of Greater European and Asian, African or Hispanic ethnicity in Ontario by sex, age group, and place of residence Place of residence
Non-rural
Rural
Age group
Drowning rate
Rate ratios (95 % confidence interval)
Asian, African or Hispanic ethnicity
Greater European ethnicity
Male
Female
Male
Female
Male
Female
0–4
0.00
0.24
0.63
0.29
0
0.85 (0.01, 8.2)
5–14
0.89
0.36
0.47
0.00
1.9 (0.8, 4.7)
–
15–24
1.86
0.00
1.57
0.11
1.2 (0.7, 2.1)
0
25–34
2.00
0.20
1.32
0.15
1.5 (0.9, 2.7)
1.3 (0.2, 7.0)
35–44
0.68
0.18
1.12
0.06
0.6 (0.3, 1.3)
3.0 (0.4, 20.9)
45–54
1.36
0.24
1.13
0.24
1.2 (0.6, 2.4)
1.0 (0.21, 4.72)
55–64
0.86
0.00
1.63
0.12
0.5 (0.2, 1.5)
0
65–74
1.55
0.00
1.1
0.12
1.4 (0.5, 4.2)
0
75?
2.24
0.56
2.1
0.43
1.1 (0.3, 3.6)
1.3 (0.2, 10.7)
All ages
1.23
0.18
1.2
0.15
1.0 (0.8, 1.3)
1.2 (0.6, 2.4)
0–4
50.3
0.00
1.62
0.00
31.2 (5.2, 186.5)
–
5–14
15.2
0.00
0.84
0.45
18.0 (2.0, 160.9)
0
15–24
49.8
0.00
3.62
0.23
13.7 (4.0, 46.9)
25–34 35–44
0.00 33.1
18.52 0.00
3.37 3.66
0.60 0.39
0 9.0 (2.1, 38.9)
45–54
74.8
15.4
2.94
0.17
25.4 (8.6, 75.5)
55–64
50.6
0.00
2.86
0.21
17.7 (4.0, 77.8)
0
65–74
35.1
0.00
4.04
0.32
8.7 (1.1, 66.4)
0
75?
51.3
52.0
4.00
0.77
12.9 (1.6, 102.9)
67.7 (6.1, 746.6)
All ages
38.6
7.2
2.97
0.34
13.0 (7.7, 22.0)
21.1 (6.0, 74.8)
0 31.1 (2.8, 342) 0 89.6 (5.6, 1,432.5)
– denotes a risk ratio that is undefined. Rate ratios express drowning rates among persons of Asian, African or Hispanic ethnicity compared to persons of Greater European ethnicity
criteria. Overall, the majority (88 %) of drowning victims were male. The highest proportion of drowning deaths was among individuals aged 15–24 years. Seventy-one percent of victims lived in a non-rural area and 27 % in a rural area. Using the name-based ethnicity classifier, 79 % of drowning victims were classified as Greater European, 9 % as Asian, 7 % as Greater African, and 5 % as Hispanic. The majority of drowning deaths occurred in open water (85 %). Comparison of Drowning Environment and Contributing Factors Table 1 provides a comparison of key environmental and contributing factors to drowning risk amongst the two groups. There was no significant difference in the sex distribution of drowning deaths. Group 2 victims tended to be younger than group 1 victims (p = 0.02). A greater proportion of drowning victims from group 2 were from non-rural areas of Ontario compared to those from group 1 (81 vs. 70 %, p = 0.04, respectively). Coroner’s Office data on personal flotation devices were available for 37 % of all drowning deaths, while
toxicology data were available for 85 % of drowning deaths. There was no significant difference in the absence of a personal flotation device between the two groups. Alcohol use as a contributing factor to the drowning, as determined by the investigating Coroner, was more common amongst victims from group 1 than group 2 (35 vs. 24 %, p = 0.04, respectively). Comorbid conditions that were deemed to potentially contribute to drowning were diabetes, epilepsy, cerebrovascular accident, psychiatric conditions, trauma, acute drug intoxication, respiratory diseases, and myocardial infarction. Drowning victims from group 1 and group 2 had documented comorbid conditions in 22 and 21 % of all cases, respectively.
Drowning Rates Sex-, age-group, and place-of-residence-stratified drowning rates are shown in Table 4. Drowning rates tended to be higher among men and among residents of rural areas, regardless of ethnicity or age (Table 4).
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J Immigrant Minority Health Fig. 2 Age-adjusted drowning mortality rates for males and females living in non-rural and rural areas. RR—Rate ratios, (95 % CI)
Drowning Rate Ratios Rate ratios and corresponding 95 % confidence intervals for the risk of drowning for group 2 individuals compared to group 1 individuals are shown in Table 4, by sex, age group, and place of residence. Age-standardized drowning rates and standardized rate ratios comparing drowning rates are shown in Fig. 2. For residents of non-rural areas of Ontario, there was no significant difference between age-adjusted mortality rates for group 2 and group 1 individuals for either men (1.3 per 100,000 person-years vs. 1.2 per 100,000 person-years, respectively; RR 1.1; 95 % CI 0.8–1.39) or women (0.19 per 100,000 person-years vs. 0.15 per 100,000 personyears, respectively; RR 1.2; 95 % CI 0.6–2.6). For male residents of rural areas, the age-adjusted mortality rate was significantly greater for group 2 than group 1 (41.2 per
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100,000 person-years vs. 3.0 per 100,000 person-years, respectively; RR 13.9; 95 % CI 8.1–23.8). For female residents of rural areas, the age-adjusted mortality rate was significantly greater for group 2 than group 1 (8.1 per 100,000 person-years vs. 0.34 per 100,000 person-years, respectively; RR 23.9; 95 % CI 6.4–89.1).
Discussion In this study of drowning deaths in Ontario over a 5-year period, individuals of Asian, Greater African, and Hispanic ethnicity living in rural Ontario drowned at a significantly higher rate than Greater Europeans living in rural Ontario. Conversely, there was no significant difference in drowning rates between the two groups living in non-rural parts of Ontario.
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Studies in the US and Netherlands have also found that ethnic minorities are at a higher risk of drowning [6, 7]. Saluja et al. determined ethnic minorities of all ages in the Netherlands had an increased relative risk of death by drowning, with those aged 15–24 having the highest risk compared to native Dutch citizens in the same age group. They postulated that ethnic minorities may not be able to afford swimming instruction or that schools heavily populated by ethnic minorities may not have access to swimming facilities. These studies, however, did not analyze drowning risk based on residence in a rural versus nonrural area. Previous studies have shown that drowning risk is directly correlated to exposure [11–13]. Thus, the increased drowning risk observed among rural residents in our study may be related to increased access to rivers, streams, lakes and quarries. Other risk factors for drowning include male sex, lack of a personal flotation device, alcohol use, medical co-morbidities (e.g., epilepsy), and an inability to swim [2, 14]. Previous studies have not found a relationship between alcohol use and ethnicity of drowning victims [15]. Interestingly, individuals of Asian, Greater African, and Hispanic ethnicities were less likely to have alcohol use implicated as a contributing factor to their drowning, which is consistent with the hypothesis that many of these drowning deaths may have been related to a lack of swimming skills, rather than misadventure. Although data on the swimming ability of drowning victims were not available in our study, there is evidence to suggest that ethnic minorities and immigrants to Ontario are less likely to be able to swim [16]. The observed increased drowning risk amongst individuals of Asian, Greater African, and Hispanic ethnicities may be related to a combination of lack of swimming ability and increased access to open, unsupervised waters in rural Ontario. Another important finding of our study is that men living in rural areas of Ontario, regardless of ethnicity, had drowning rates that were 2–25 times higher than men living in non-rural areas. In Canada, the risk of drowning among men varies by age and ranges from a low of 0.48 per 100,000 person-years among males age 0–1 to a high of 3.07 among males age 15–24 [2]. Data on differences between urban and rural drowning rates in Canada, however, have not been previously published. A small study in China found that children aged 1–14 living in rural areas had a drowning rate approximately six times greater than children living in urban areas [17]. In contrast, a study in the US did not find a significant difference between rates of drowning in urban versus rural areas [18]. Neither study investigated the influence of ethnicity on drowning rate. The reasons for the observed increased risk is not known, but are likely multifactorial and may include increased access to open, unsupervised water.
This study has several limitations that warrant consideration when interpreting our results. First, data on ethnicity and country of origin were not available from the Coroner’s office and had to be inferred based on the names of decedents. Specifically, ethnicity was used as a surrogate to infer country of origin. While the ethnicity classifier used in this study has been previously validated, namebased ethnicity classification methods are a relatively new tool in epidemiological studies [19]. Based on the precision statistics of the ethnicity classifier we used, estimates for Greater European and Asian origins were more likely to be accurate (precision = 0.96 and 0.82, respectively), while estimates for Greater Africans and Hispanics were less likely to be accurate (precision = 0.56 and 0.68, respectively). In addition, Aboriginal people (First Nations, Metis, and Inuit) constitute about 2 % of the population of Ontario and often live in rural areas. The name ethnicity classifier does not identify Aboriginal names as such. Thus, if Aboriginal names were misclassified as being of Hispanic, Greater African, or Asian ethnicity, drownings of Aboriginal people may have contributed to the excess drowning deaths observed among people living in rural areas who were deemed to be of non-Greater European ethnicity. Ideally, information on place of birth and ethnicity would be documented on death certificates to facilitate epidemiologic studies of mortality among different ethnicities, but this is not the current practice in Canada. Second, our study is based on data from a single Canadian province, and it is unknown if our results can be generalized to the rest of Canada or to other countries. Third, due to the small number of drowning victims among each of the ethnic groups studied, it was necessary to pool the ethnic groups together for the analysis. This prevents us from making direct conclusions about specific ethnicities. Further, although our results demonstrate an impressive relative difference associated with ethnicity and drowning it is important to stress that the absolute difference is small. Fourth, we used 2006 Census data as our midpoint year of our study to determine the ethnic population of Ontario. Thus, our results may be subject to slight inaccuracies due to population changes over the period 2004–2008. However, it is reassuring to note that the ten largest ethnic groups in Ontario remained unchanged between census years 1996, 2001 and 2006 [5]. Finally, our study does not provide information on the incidence of near-drowning events, which are estimated to occur about five times more frequently than drowning deaths, and which can provide valuable insights into the prevention of drownings [1]. We also do not have detailed data about the specific activities of drowning victims at the time of their death. This study confirms findings from developing countries that individuals living in rural areas are at an increased risk
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of drowning. Our study also showed that men and women of Asian, Greater African, or Hispanic ethnicity living in rural Ontario had significantly higher drowning rates than those of Great European ethnicity. Although this only translates into approximately 20 additional drowning deaths per year, we still believe targeting drowning prevention strategies towards this group is important since drowning deaths are preventable and most often affect young and otherwise healthy individuals. We hypothesize that increased access to open water in combination with lower levels of exposure to swimming and water safety skills may explain this finding. Consideration should also be given to educational campaigns about basic water safety skills directed towards certain ethnicities, specifically persons who have recently moved to a rural environment. Drowning prevention organizations may also consider increasing the use of outreach programs that work specifically with cultural organizations from different ethnic groups. To our knowledge, our study is the first to characterize ethnic differences in drowning rates in Ontario. It is concerning that certain ethnicities in rural areas may lack swimming skills and knowledge, possibly leading to more preventable drowning deaths in some ethnic groups. We believe that additional studies should address potential socioeconomic and geographic boundaries that may create differences in access to swimming skills and water safety knowledge. In addition, further research should attempt to quantify swimming knowledge among ethnic minorities living in urban and rural areas. Acknowledgments Preliminary findings from this study were presented at the 2011 World Conference on Drowning Prevention, Danang, Vietnam, May 10, 2011. This project was funded by an unrestricted Grant from the Lifesaving Society of Ontario. The funder had no input on study design, data acquisition, data interpretation, or manuscript writing. The authors thank Dr. Jim Edwards, June Lindsell, and the Office of the Chief Coroner of Ontario for support, valued input, and access to data. The authors wish to thank Angela Prencipe of the Toronto Region Statistics Canada Research Data Centre for guidance in accessing Census data and Jing Shen for expert assistance in programming and data extraction. The authors also wish to thank Marisa Creatore of the Centre for Research on Inner City Health for her assistance in using the Statistics Canada Postal Code Conversion File. The Centre for Research on Inner City Health gratefully acknowledges the support of the Ontario Ministry of Health and Long-Term Care. The results and conclusions are those of the authors, and no official endorsement by any of the above organizations is intended or should be inferred.
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2. Royal Lifesaving Society Canada. The national drowning trends report: 1991–2000. Lifesaving Society of Canada’s website. http://www.lifesaving.ca/. Accessed 12 Jan 2013. 3. Smartrisk. The economic burden of injury. www.smartrisk.ca/ downloads/burden/Canada2009/EBI-Eng-Final.pdf. Accessed 19 March 2012. 4. Lewis P. Census highlights: factsheet 7—immigration and citizenship. 2006. http://www.fin.gov.on.ca/en/economy/demograp hics/census/cenhi06-7.html. Accessed 8 Nov 2012. 5. Chui T, Tran K, Maheux H. Canada’s Ethnocultural Mosaic, Census. 2006. http://www12.statcan.ca/census-recensement/2006/as-sa/ 97-562/pdf/97-562-XIE2006001.pdf. Accessed 8 Sept 2013. 6. Saluja G, Brenner RA, Trumble AC, Smith GS, Schroeder T, Cox C. Swimming pool drownings among US residents aged 5–24 years: understanding racial/ethnic disparities. Am J Public Health. 2006; 96:728–33. doi:10.2105/AJPH.2004.057067. 7. Stirbu I. Injury mortality among ethnic minority groups in the Netherlands. J Epidemiol Community Health. 2006;60:249–55. doi:10.1136/jech.2005.037325. 8. Quan L, Crispin B, Bennett E, Gomez A. Beliefs and practices to prevent drowning among Vietnamese-American adolescents and parents. Inj Prev. 2006;12:427–9. doi:10.1136/ip.2006.011486. 9. Wilkins R. Use of postal codes and addresses in the analysis of health data. Health Rep. 1993;5:157–77. 10. Ambekar A, Ward C, Mohammed J, Male S, Skiena S. Nameethnicity classification from open sources. In: Proceedings of the 15th ACM SIGKDD international conference on Knowledge discovery and data mining, 2009, p 49–58. 11. Gulliver P, Begg D. Usual water-related behaviour and ‘‘neardrowning’’ incidents in young adults. Aust N Z J Public Health. 2005;29:238–43. 12. Rahman A, Giashuddin SM, Svanstro¨m L, Rahman F. Drowning—a major but neglected child health problem in rural Bangladesh: implications for low income countries. Int J Inj Contr Saf Promot. 2006;13:101–5. doi:10.1080/17457300500172941. 13. Rahman F, Bose S, Linnan M, Rahman A, Mashreky S, Haaland B, Finkelstein E. Cost-effectiveness of an injury and drowning prevention program in Bangladesh. Pediatrics. 2012;130:1621–8. 14. Cummings P, Mueller BA, Quan L. Association between wearing a personal floatation device and death by drowning among recreational boaters: a matched cohort analysis of United States Coast Guard data. Inj Prev. 2011;17:156–9. doi:10.1136/ip.2010. 028688. 15. Wintemute GJ, Teret S, Kraus J, Wright M. Alcohol and drowning: an analysis of contributing factor and discussion of criteria for case selection. Accid Anal Prev. 1990;22:291–6. 16. Iltan C. In a nation defined by water, new Canadians struggle to stay safe. The Globe and Mail. 15 July 2010. 17. Fang Y, Dai L, Jaung MS, Chen X, Yu S, Xiang H. Child drowning deaths in Xiamen city and suburbs, People’s Republic of China, 2001 5. Inj Prev. 2007;13:339–43. doi:10.1136/ip.2007. 016683. 18. Quan LL, Cummings PP. Characteristics of drowning by different age groups. Inj Prev. 2003;9:163–8. 19. Mateos P. A review of name-based ethnicity classification methods and their potential in population studies. Popul Space Place. 2007;13:243–63. doi:10.1002/psp.457.
ORIGINAL PAPER
Ethnic Differences in Drowning Rates in Ontario, Canada Zane R. Gallinger • Michael Fralick Stephen W. Hwang
•
Ó Springer Science+Business Media New York 2014
Abstract The scientific literature suggests ethnicity may be a risk factor for drowning. Ontario, Canada is one of the most ethnically diverse places in the world. The objective of our study was to determine if Asians, Africans and Hispanics were at an increased risk of drowning compared to Greater Europeans. Ethnicity served as a surrogate for country of origin. Using Coroner’s reports, all unintentional drowning deaths in Ontario from 2004 to 2008 were reviewed. The ethnicity of drowning victims was estimated using a previously validated name-based ethnicity classifier. Age-standardized drowning rates were calculated by sex and place of residence (rural vs. non-rural) for people of each ethnicity group using the method of direct standardization. For residents of Ontario living in rural areas, the age-standardized drowning rate was significantly higher among men of Asian, African, or Hispanic ethnicity compared to men of Greater European ethnicity (RR 13.9; 95 % CI 8.1–23.8) and for women of Asian, African, or Hispanic ethnicity compared to women of Greater European ethnicity (RR 23.9; 95 % CI 6.4–89.1). These highrisk individuals need to be considered when developing drowning prevention strategies. Z. R. Gallinger M. Fralick Internal Medicine Residents, Faculty of Medicine, University of Toronto, Toronto, Canada e-mail: [email protected] S. W. Hwang (&) Centre for Research on Inner City Health, The Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, 30 Bond St., Toronto, ON M5B 1W8, Canada e-mail: [email protected] S. W. Hwang Division of General Internal Medicine, Department of Medicine, University of Toronto, Toronto, Canada
Keywords Drowning Ethnicity Ontario Harm prevention Swimming Immigrant
Introduction Drowning is the second leading cause of unintentional injury death worldwide, after motor vehicle injuries [1]. In Ontario, Canada’s largest province, approximately 150 drownings occur each year, representing a serious health concern [2]. In 2004, drowning deaths and hospitalizations for drownings and near-drownings in Ontario resulted in approximately 33 million dollars in direct and indirect costs [3]. The Canadian Lifesaving Society and the Canadian Red Cross promote drowning prevention programs for the general public, but it is unclear if specific populations require increased efforts or targeted interventions for drowning prevention. Approximately 28 % of Ontarians, or 3.4 million people, are immigrants who were born outside of Canada, making Ontario one of the most diverse places in the world [4]. Recent census data indicate that Ontario’s citizens represent over 200 different ethnicities [5]. Furthermore, the majority (65 %) of newcomers to Canada are from developing nations within Asia where swimming skills are not routinely taught [4]. Despite Ontario’s ethnic diversity, we are unaware of any studies examining the ethnicity of drowning victims in Ontario. Studies in the United States and the Netherlands have found a higher risk of drowning among certain ethnic groups, possibly related to a lack of swimming and water safety skills [6, 7]. In addition, specific cultural beliefs as well as a lack of familiarity and exposure to swimming environment may play a role in how individuals approach aquatic environments [8].
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The objective of this study was to determine if certain ethnic groups in Ontario are at increased risk of drowning. Because both the risk of drowning and the proportion of individuals belonging to different ethnicities were expected to vary widely in rural compared to non-rural areas, we conducted separate analyses of drowning rates in rural and non-rural areas of Ontario.
Methods Study Setting Ontario is the largest province in Canada by population (13.6 million) and second largest by land mass (1 million km2). Ontario has over 250,000 freshwater lakes, four of which make up the Great Lakes Basin, which is the largest continuous body of fresh water in the world. Over 98 % of Ontario residents live within the Great Lakes Basin. According to the 2006 Canadian Census, there were approximately 2,745,200 visible minorities living in Ontario (54 % of Canada’s total visible minority population) [4]. Approximately 23 % of Ontario residents identify themselves as visible minorities, with the three largest groups being South Asian, Chinese, and Black [5]. About 41 % of Ontario residents report being of British Isles origins, and 36 % report being of other European origins [5]. Drowning Case Identification Data related to drowning deaths in Ontario, Canada, were obtained from the Office of the Chief Coroner, which investigates all drowning deaths in the province. Unintentional drowning deaths occurring during the 5-year period from January 1, 2004, through December 31, 2008, were eligible for inclusion in the study. At the time of the study, the 2006 Canadian census was the most recent available. The 5-year period 2004–2008 was selected to be centered around this year. Drowning deaths were excluded if the victim was not a resident of Ontario or if the victim did not have a residential postal code recorded in the Coroner’s database. Drowning deaths that occurred in a bathtub were excluded because they were not plausibly related to swimming ability or water safety skills. Intentional drowning deaths, as determined by the Coroner to be due to suicide or homicide, were also excluded. Demographic Information Demographic information, including each drowning victim’s age, sex, and residential postal code, were obtained from the Office of the Chief Coroner. When the Coroner
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attends the scene of a drowning, the postal code of the drowning victim is collected from the victim’s driver’s license or another available form of identification. Age was grouped into the following categories: 0–4, 5–14, 15–24, 25–34, 35–44, 45–54, 55–64, 65–74, and 75? years. Medical comorbidities, autopsy findings, and toxicology results were also obtained from the Coroner’s records (Table 1). Toxicology testing is routinely ordered on all drowning victims. Residential postal codes were used to classify decedents as residents of rural or non-rural areas of Ontario. This process used a previously validated algorithm, the Postal Code Conversion File Plus (PCCF?) [9]. Each postal code was mapped to a rural area, or to a Census Metropolitan Area (CMA), which is by definition a non-rural area. Ethnicity Classification Since the Office of the Chief Coroner does not obtain information on the ethnicity or country of birth of decedents, the following procedures were used to impute the ethnicity of drowning victims. The names of drowning victims were entered into a validated name-ethnicity classification program [10]. The name-ethnicity classification reported precision statistics (Table 2), which are comparable with most ethnicity classification systems [10]. This computerized classification algorithm identifies probable ethnicity based on first and last name. The algorithm classifies individuals into one of three primary ethnic categories (Asian, Greater African, or Greater European) and an ethnic subcategory within each of these primary categories (Fig. 1). These ethnicities were chosen by the researchers who developed the classification algorithm because their model determined they had the highest accuracy and precisions. These name-based ethnic categories were then converted to corresponding ethnic groups used by Statistics Canada in the 2006 Census (Table 3). The number of drowning deaths was tabulated by sex, age group, place of residence (rural vs. non-rural), and ethnic group (Asian, Greater African, Hispanic, and Greater European). Since the number of drowning victims within each ethnic subgroup of Asian, African, and Hispanic were relatively small, these groups were combined and analyzed as a single group. Ethnicity was used as a surrogate marker for country of origin. Of note, the ethnicity classifier included Hispanic in the Greater European group; however, we included these individuals in our nonGreater European group. Our focus was on identifying individuals of Asian, Greater African, and Hispanic decent, who together account for the vast majority of visible minorities in Ontario [5]. According to the 2006 Census, over 75 % of visible minorities were born outside of Canada [5].
J Immigrant Minority Health Table 1 Characteristics of unintentional drowning victims in Ontario, 2004–2008, by ethnicity (n = 492)
Characteristic
Asian, African or Hispanic ethnicity N (%)
Greater European ethnicity
N (%)
Male
87 (86)
347 (89)
Female Age group
14 (14)
44 (11)
0–4
3 (3)
13 (3)
5–14
12 (12)
18 (5)
15–24
21 (21)
64 (16)
25–34
19 (19)
50 (13)
35–44
11 (11)
57 (15)
45–54
18 (18)
61 (16)
55–64
6 (6)
56 (14)
65–74
5 (5)
32 (8)
75?
6 (6)
40 (10)
Non-rural
82 (81)
274 (70)
Rural
19 (19)
117 (30)
Greater European (other than Hispanic) Asian
– 43 (43)
391 (100) –
Greater African
34 (34)
–
Hispanic
24 (23)
–
Open water
79 (78)
337 (86)
Public pool
6 (6)
8 (2)
Private pool
15 (15)
30 (8)
1 (1)
13 (3)
Sex
0.58
0.02
Place of residence
0.04
Ethnicitya
n/a
Setting of drowningb a
See text for details on methods used to impute ethnicity
b
Drownings occurring in bathtubs were excluded
c
Comorbid conditions that were deemed to potentially contribute to drowning were diabetes, epilepsy, cerebrovascular accident, psychiatric conditions, trauma, acute drug intoxication, respiratory diseases, and myocardial infarction
Pond/quarry/casual water Unspecified/other
p value
0.02
(0)
3 (1)
Absence of personal flotation device
20 (20)
66 (17)
0.59
Alcohol use as contributing factor
24 (24)
138 (35)
0.03
None
76 (75)
283 (72)
One present
21 (21)
85 (22)
4 (4)
23 (6)
Comorbid conditionsc
Two or more present
Ethics Statement The names of drowning victims were entered into the ethnicity classification program at the Office of the Coroner, which is a secure, locked facility. To protect the confidentiality of decedents and their families, only the ethnicity of decedents and not their names were recorded in the study database. After the postal code of decedents was used to determine rural versus non-rural place of residence, the postal code was deleted from the database. This study
0.72
was approved by the St. Michael’s Hospital Research Ethics Board. Statistical Analysis Characteristics of drowning victims of Greater European (group 1) and the combined group of Asian, Greater African, and Hispanic ethnicities (group 2) were compared using the Chi square test. Statistical significance was defined as a p value less than 0.05.
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J Immigrant Minority Health Table 2 Name-based ethnic categories from ethnicity classifier and corresponding precision, recall, and F-score [10]
Table 3 Name-based ethnic categories and corresponding census ethnic groups used to classify individuals
Name-based ethnic categories
Precision
Recall
F-score
Name-based ethnic categories
Census ethnic groups
Asian
0.82
0.83
0.82
Asian
West Asian, South Asian, East Asian, and Southeast Asian
Hispanic
0.68
0.62
0.65
Greater African
0.56
0.75
0.65
Greater African
African
0.95
Hispanic Greater European (other than Hispanic)
Hispanic All other ethnic groups
Greater European
0.96
0.93
Data on the total population of Ontario, stratified by sex, age group, place of residence (rural vs. non-rural), and ethnicity, were obtained from the 2006 Canadian Census. Of 144 sex-, age group-, place of residence- and ethnicityspecific groups, the population estimates for 16 groups were suppressed by Statistics Canada due to low counts in the census sample used to generate the population estimate. The population in each of these groups was estimated by taking the mean of the adjacent age groups within the same sex-, place of residence-, and ethnicity-specific stratum. Drowning rates for each ethnicity grouping were calculated by sex, age group, and place of residence. Rates were expressed as deaths per 100,000 person-years. Rates ratios comparing drowning rates between group 1 and group 2 were calculated by sex, age group, and place of residence. Fig. 1 Name-based ethnic categories used for ethnicity classification [10]
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Age-standardized drowning rates were calculated for group 2 using the method of direct standardization, with group 1 serving as the standard population. Standardized rate ratios comparing drowning rates among people of group 1 and group 2 were calculated by sex and place of residence.
Results Drowning Cases Between 2004 and 2008, a total of 492 Ontario residents died of unintentional drowning and met study inclusion
J Immigrant Minority Health Table 4 Drowning rates (deaths per 100,000 person-years) among persons of Greater European and Asian, African or Hispanic ethnicity in Ontario by sex, age group, and place of residence Place of residence
Non-rural
Rural
Age group
Drowning rate
Rate ratios (95 % confidence interval)
Asian, African or Hispanic ethnicity
Greater European ethnicity
Male
Female
Male
Female
Male
Female
0–4
0.00
0.24
0.63
0.29
0
0.85 (0.01, 8.2)
5–14
0.89
0.36
0.47
0.00
1.9 (0.8, 4.7)
–
15–24
1.86
0.00
1.57
0.11
1.2 (0.7, 2.1)
0
25–34
2.00
0.20
1.32
0.15
1.5 (0.9, 2.7)
1.3 (0.2, 7.0)
35–44
0.68
0.18
1.12
0.06
0.6 (0.3, 1.3)
3.0 (0.4, 20.9)
45–54
1.36
0.24
1.13
0.24
1.2 (0.6, 2.4)
1.0 (0.21, 4.72)
55–64
0.86
0.00
1.63
0.12
0.5 (0.2, 1.5)
0
65–74
1.55
0.00
1.1
0.12
1.4 (0.5, 4.2)
0
75?
2.24
0.56
2.1
0.43
1.1 (0.3, 3.6)
1.3 (0.2, 10.7)
All ages
1.23
0.18
1.2
0.15
1.0 (0.8, 1.3)
1.2 (0.6, 2.4)
0–4
50.3
0.00
1.62
0.00
31.2 (5.2, 186.5)
–
5–14
15.2
0.00
0.84
0.45
18.0 (2.0, 160.9)
0
15–24
49.8
0.00
3.62
0.23
13.7 (4.0, 46.9)
25–34 35–44
0.00 33.1
18.52 0.00
3.37 3.66
0.60 0.39
0 9.0 (2.1, 38.9)
45–54
74.8
15.4
2.94
0.17
25.4 (8.6, 75.5)
55–64
50.6
0.00
2.86
0.21
17.7 (4.0, 77.8)
0
65–74
35.1
0.00
4.04
0.32
8.7 (1.1, 66.4)
0
75?
51.3
52.0
4.00
0.77
12.9 (1.6, 102.9)
67.7 (6.1, 746.6)
All ages
38.6
7.2
2.97
0.34
13.0 (7.7, 22.0)
21.1 (6.0, 74.8)
0 31.1 (2.8, 342) 0 89.6 (5.6, 1,432.5)
– denotes a risk ratio that is undefined. Rate ratios express drowning rates among persons of Asian, African or Hispanic ethnicity compared to persons of Greater European ethnicity
criteria. Overall, the majority (88 %) of drowning victims were male. The highest proportion of drowning deaths was among individuals aged 15–24 years. Seventy-one percent of victims lived in a non-rural area and 27 % in a rural area. Using the name-based ethnicity classifier, 79 % of drowning victims were classified as Greater European, 9 % as Asian, 7 % as Greater African, and 5 % as Hispanic. The majority of drowning deaths occurred in open water (85 %). Comparison of Drowning Environment and Contributing Factors Table 1 provides a comparison of key environmental and contributing factors to drowning risk amongst the two groups. There was no significant difference in the sex distribution of drowning deaths. Group 2 victims tended to be younger than group 1 victims (p = 0.02). A greater proportion of drowning victims from group 2 were from non-rural areas of Ontario compared to those from group 1 (81 vs. 70 %, p = 0.04, respectively). Coroner’s Office data on personal flotation devices were available for 37 % of all drowning deaths, while
toxicology data were available for 85 % of drowning deaths. There was no significant difference in the absence of a personal flotation device between the two groups. Alcohol use as a contributing factor to the drowning, as determined by the investigating Coroner, was more common amongst victims from group 1 than group 2 (35 vs. 24 %, p = 0.04, respectively). Comorbid conditions that were deemed to potentially contribute to drowning were diabetes, epilepsy, cerebrovascular accident, psychiatric conditions, trauma, acute drug intoxication, respiratory diseases, and myocardial infarction. Drowning victims from group 1 and group 2 had documented comorbid conditions in 22 and 21 % of all cases, respectively.
Drowning Rates Sex-, age-group, and place-of-residence-stratified drowning rates are shown in Table 4. Drowning rates tended to be higher among men and among residents of rural areas, regardless of ethnicity or age (Table 4).
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J Immigrant Minority Health Fig. 2 Age-adjusted drowning mortality rates for males and females living in non-rural and rural areas. RR—Rate ratios, (95 % CI)
Drowning Rate Ratios Rate ratios and corresponding 95 % confidence intervals for the risk of drowning for group 2 individuals compared to group 1 individuals are shown in Table 4, by sex, age group, and place of residence. Age-standardized drowning rates and standardized rate ratios comparing drowning rates are shown in Fig. 2. For residents of non-rural areas of Ontario, there was no significant difference between age-adjusted mortality rates for group 2 and group 1 individuals for either men (1.3 per 100,000 person-years vs. 1.2 per 100,000 person-years, respectively; RR 1.1; 95 % CI 0.8–1.39) or women (0.19 per 100,000 person-years vs. 0.15 per 100,000 personyears, respectively; RR 1.2; 95 % CI 0.6–2.6). For male residents of rural areas, the age-adjusted mortality rate was significantly greater for group 2 than group 1 (41.2 per
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100,000 person-years vs. 3.0 per 100,000 person-years, respectively; RR 13.9; 95 % CI 8.1–23.8). For female residents of rural areas, the age-adjusted mortality rate was significantly greater for group 2 than group 1 (8.1 per 100,000 person-years vs. 0.34 per 100,000 person-years, respectively; RR 23.9; 95 % CI 6.4–89.1).
Discussion In this study of drowning deaths in Ontario over a 5-year period, individuals of Asian, Greater African, and Hispanic ethnicity living in rural Ontario drowned at a significantly higher rate than Greater Europeans living in rural Ontario. Conversely, there was no significant difference in drowning rates between the two groups living in non-rural parts of Ontario.
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Studies in the US and Netherlands have also found that ethnic minorities are at a higher risk of drowning [6, 7]. Saluja et al. determined ethnic minorities of all ages in the Netherlands had an increased relative risk of death by drowning, with those aged 15–24 having the highest risk compared to native Dutch citizens in the same age group. They postulated that ethnic minorities may not be able to afford swimming instruction or that schools heavily populated by ethnic minorities may not have access to swimming facilities. These studies, however, did not analyze drowning risk based on residence in a rural versus nonrural area. Previous studies have shown that drowning risk is directly correlated to exposure [11–13]. Thus, the increased drowning risk observed among rural residents in our study may be related to increased access to rivers, streams, lakes and quarries. Other risk factors for drowning include male sex, lack of a personal flotation device, alcohol use, medical co-morbidities (e.g., epilepsy), and an inability to swim [2, 14]. Previous studies have not found a relationship between alcohol use and ethnicity of drowning victims [15]. Interestingly, individuals of Asian, Greater African, and Hispanic ethnicities were less likely to have alcohol use implicated as a contributing factor to their drowning, which is consistent with the hypothesis that many of these drowning deaths may have been related to a lack of swimming skills, rather than misadventure. Although data on the swimming ability of drowning victims were not available in our study, there is evidence to suggest that ethnic minorities and immigrants to Ontario are less likely to be able to swim [16]. The observed increased drowning risk amongst individuals of Asian, Greater African, and Hispanic ethnicities may be related to a combination of lack of swimming ability and increased access to open, unsupervised waters in rural Ontario. Another important finding of our study is that men living in rural areas of Ontario, regardless of ethnicity, had drowning rates that were 2–25 times higher than men living in non-rural areas. In Canada, the risk of drowning among men varies by age and ranges from a low of 0.48 per 100,000 person-years among males age 0–1 to a high of 3.07 among males age 15–24 [2]. Data on differences between urban and rural drowning rates in Canada, however, have not been previously published. A small study in China found that children aged 1–14 living in rural areas had a drowning rate approximately six times greater than children living in urban areas [17]. In contrast, a study in the US did not find a significant difference between rates of drowning in urban versus rural areas [18]. Neither study investigated the influence of ethnicity on drowning rate. The reasons for the observed increased risk is not known, but are likely multifactorial and may include increased access to open, unsupervised water.
This study has several limitations that warrant consideration when interpreting our results. First, data on ethnicity and country of origin were not available from the Coroner’s office and had to be inferred based on the names of decedents. Specifically, ethnicity was used as a surrogate to infer country of origin. While the ethnicity classifier used in this study has been previously validated, namebased ethnicity classification methods are a relatively new tool in epidemiological studies [19]. Based on the precision statistics of the ethnicity classifier we used, estimates for Greater European and Asian origins were more likely to be accurate (precision = 0.96 and 0.82, respectively), while estimates for Greater Africans and Hispanics were less likely to be accurate (precision = 0.56 and 0.68, respectively). In addition, Aboriginal people (First Nations, Metis, and Inuit) constitute about 2 % of the population of Ontario and often live in rural areas. The name ethnicity classifier does not identify Aboriginal names as such. Thus, if Aboriginal names were misclassified as being of Hispanic, Greater African, or Asian ethnicity, drownings of Aboriginal people may have contributed to the excess drowning deaths observed among people living in rural areas who were deemed to be of non-Greater European ethnicity. Ideally, information on place of birth and ethnicity would be documented on death certificates to facilitate epidemiologic studies of mortality among different ethnicities, but this is not the current practice in Canada. Second, our study is based on data from a single Canadian province, and it is unknown if our results can be generalized to the rest of Canada or to other countries. Third, due to the small number of drowning victims among each of the ethnic groups studied, it was necessary to pool the ethnic groups together for the analysis. This prevents us from making direct conclusions about specific ethnicities. Further, although our results demonstrate an impressive relative difference associated with ethnicity and drowning it is important to stress that the absolute difference is small. Fourth, we used 2006 Census data as our midpoint year of our study to determine the ethnic population of Ontario. Thus, our results may be subject to slight inaccuracies due to population changes over the period 2004–2008. However, it is reassuring to note that the ten largest ethnic groups in Ontario remained unchanged between census years 1996, 2001 and 2006 [5]. Finally, our study does not provide information on the incidence of near-drowning events, which are estimated to occur about five times more frequently than drowning deaths, and which can provide valuable insights into the prevention of drownings [1]. We also do not have detailed data about the specific activities of drowning victims at the time of their death. This study confirms findings from developing countries that individuals living in rural areas are at an increased risk
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of drowning. Our study also showed that men and women of Asian, Greater African, or Hispanic ethnicity living in rural Ontario had significantly higher drowning rates than those of Great European ethnicity. Although this only translates into approximately 20 additional drowning deaths per year, we still believe targeting drowning prevention strategies towards this group is important since drowning deaths are preventable and most often affect young and otherwise healthy individuals. We hypothesize that increased access to open water in combination with lower levels of exposure to swimming and water safety skills may explain this finding. Consideration should also be given to educational campaigns about basic water safety skills directed towards certain ethnicities, specifically persons who have recently moved to a rural environment. Drowning prevention organizations may also consider increasing the use of outreach programs that work specifically with cultural organizations from different ethnic groups. To our knowledge, our study is the first to characterize ethnic differences in drowning rates in Ontario. It is concerning that certain ethnicities in rural areas may lack swimming skills and knowledge, possibly leading to more preventable drowning deaths in some ethnic groups. We believe that additional studies should address potential socioeconomic and geographic boundaries that may create differences in access to swimming skills and water safety knowledge. In addition, further research should attempt to quantify swimming knowledge among ethnic minorities living in urban and rural areas. Acknowledgments Preliminary findings from this study were presented at the 2011 World Conference on Drowning Prevention, Danang, Vietnam, May 10, 2011. This project was funded by an unrestricted Grant from the Lifesaving Society of Ontario. The funder had no input on study design, data acquisition, data interpretation, or manuscript writing. The authors thank Dr. Jim Edwards, June Lindsell, and the Office of the Chief Coroner of Ontario for support, valued input, and access to data. The authors wish to thank Angela Prencipe of the Toronto Region Statistics Canada Research Data Centre for guidance in accessing Census data and Jing Shen for expert assistance in programming and data extraction. The authors also wish to thank Marisa Creatore of the Centre for Research on Inner City Health for her assistance in using the Statistics Canada Postal Code Conversion File. The Centre for Research on Inner City Health gratefully acknowledges the support of the Ontario Ministry of Health and Long-Term Care. The results and conclusions are those of the authors, and no official endorsement by any of the above organizations is intended or should be inferred.
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