Penetrating trauma in Ontario emergency departments: a population-based study

EM Advances

CJEM 2007;9(1):16-20

Abstract

Résumé

Background

Penetrating trauma results in high morbidity and mortality in many countries. An estimated 229 000 people die from firearm-related deaths around the world each year.1 In the United States, much research has been conducted to determine the burden and costs of this type of injury. In 2000 there were an estimated 16 765 victims in the US who were killed by firearms and a further 776 deaths from unintentional firearm injuries.2 For each death there are many more hospitalizations and ED visits. For example, one US study estimated that there were 64 200 ED visits in 1 year for gunshot wounds alone.3 In New Mexico, researchers reported similar rates of knife-related and stabbing-related hospitalizations.4 Although the rate of firearm-related injuries and deaths has traditionally been lower in Canada, the costs to the victim and the health care system are substantial in both countries.5,6

Penetrating trauma related to gunshot wounds has been dubbed "the new public health issue" in Canada.7 Among young adults (15-24 years) firearms were the third leading cause of death in 1990.8,9 The overall mortality rate from gunshot wounds in Canada has declined since 1979, when it was 10.6 per 100 000 for Canadian men; in 2002 the rate had dropped to 4.9 per 100 000.10 In 1991, the health care costs associated with gunshot wounds in Canada were estimated to be $63 million.11 Despite the costs to victims, their families and the health care system, and despite the fact that many of these injuries can be prevented, there has been little published regarding ED visits for penetrating trauma. Gaining an understanding of the epidemiology and the magnitude of health services use for all kinds of penetrating trauma in Canada is an important step in prevention. The goal of this study is to describe the epidemiology of penetrating-trauma-related visits to Ontario EDs. This includes comparing gun-related injuries to injuries associated with knives and sharp objects, and presenting population-based rates by gender, age, acuity, intent and admission rates.

Methods

All EDs in the province of Ontario (pop. 12 400 000) submit abstracted data on ED visits to the National Ambulatory Care Reporting System (NACRS), maintained by the Canadian Institute for Health Information. This database includes urban, suburban and rural hospital EDs in the province, as well as pediatric, tertiary care and community hospitals. In all, 180 hospitals are required to submit data, including demographic information about the patient (i.e., age, sex, geographic area of residence), the reasons for the visit (i.e., external causes of injury codes according to the Canadian Enhancement to the International Statistical Classification of Diseases and Related Problems, 10th rev [ICD-10-CA]), where the patient went after leaving the ED (i.e., either admitted to hospital or sent home) and other diagnostic information. Our study included patients with an ICD-10-CA code related to contact with knife, sword or dagger, and firearm injuries, including those classified as unintentional/unknown intent, intentional, and self-inflicted injuries. Table 1 includes the codes selected for this study and the description provided by the ICD-10-CA.

All patients seen in Ontario EDs between Apr. 1, 2002, and Mar. 31, 2003, for an injury related to a firearm, knife, or sharp object, (i.e., classified with the codes mentioned above) were included in our study. Using the Canadian Emergency Department Triage and Acuity Scale (CTAS),12 acuity of injuries were categorized as Level I (Resuscitation), II (Emergent), III (Urgent), IV (Less Urgent) and V (Non Urgent). Data are presented as rates per 100 000 population (based on population estimates from Statistics Canada 2001 census.13 The rates were calculated by using the number of ED visits in that category as the numerator, and the relevant population (i.e., all Ontario, specific age groups, or gender) as the denominator. Data were analyzed using SAS software.

Results

Out of the 4 921 085 ED visits captured in the NACRS data, 1 211 500 were for injury-related causes, and 40 240 (3.3%) of those were coded as penetrating trauma injuries, which resulted in an annual ED visit rate for penetrating trauma of 324.5 per 100 000 population. Twenty-six thousand visits (65%) were made by males (466.2/100 000), and 14 240 by females (244.1/100 000). Most penetrating trauma in the ED is a result of knives or sharp objects (39 654 visits, or 98%), with firearms implicated in only 586 visits. The injury rate for firearm-related injuries was 4.7 per 100 000, versus 319.8 per 100 000 for knives/ sharp-object-related injuries. The majority of ED visits for penetrating trauma were classified as unintentional or intent unknown.

Table 2 depicts the epidemiology of penetrating trauma for both firearm-related injuries and injuries from knives/sharp objects by ED visit rates, gender, age group, intent, triage score and hospitalization. Age is associated with the incidence of penetrating trauma. The 15-24-year age group had the highest rate of ED visits for both firearms and knives/sharp objects (14.9 for firearms and 673.5 for knives). The injury rates in this age group were more than twice as high as the corresponding rate among adults 25-64 years (4.2 and 355.8 for firearms and knives, respectively).

Both types of penetrating trauma can be associated with high-acuity injuries. The frequency distribution of penetrating trauma by CTAS score is presented in Table 2. Knives were less likely to result in high-acuity (CTAS Level I or II) injuries than were firearms (1234/39 654 [3.1%] v. 234/586 [39.9%]); however, the number of high-acuity knife-related injuries was more than 5 times greater than those related to firearms (n = 1234 v. n = 234). Hospital admission is a fairly common outcome, with 151 over the study period for firearm-related injuries, and a corresponding 1455 admissions for injuries due to knives or sharp objects, an almost 10-fold difference. However, firearm-related injuries were more likely to result in admission (151/586 [25.7%]) than were knife-related injuries (1455/39 654 [3.7%]). The overall number of deaths in hospital caused by knives (n = 26) and guns (n = 30) were similar even though the case-fatality rate in hospital was much higher for firearm-related injuries (5%) than for knives/sharp-objects-related injuries (0.06%).

Discussion

In 2002-03, penetrating trauma in Ontario was responsible for about 3% of all ED visits for trauma, with more than 40 000 ED visits resulting from guns, knives and other sharp objects. The overall firearm-related injury rate of 4.7 per 100 000 is significantly lower than the estimated corresponding value reported by some states in the US (e.g., 34.3 in New Mexico and 30.9 in Massachusetts4,14); however, it is of concern in Canada nonetheless.3 Our data reinforce an earlier article by Chapdelaine and colleagues8 suggesting that penetrating trauma is most common among males and young people. Although about 10% of these ED visits are classified as intentional (assault or self-harm), the majority are coded as unintentional or of unknown intent. This percentage demonstrates a markedly different pattern from mortality data, where suicides make up about four-fifths of all firearm-related deaths in Canada.10

Not all penetrating trauma falls within a triage category reflecting high acuity. Our data suggest that firearms cause more serious injuries on average than do knives. Overall, only 3.1% of knife-related injuries were triaged as high acuity in the ED and only 3.7% required hospital admission, compared with 39.9% and 25.7%, respectively, for firearm-related injuries. Surprisingly, 10.2% of the firearm-related injuries were classified as Non Urgent (Level V). This is likely because injuries due to BB guns and air rifles were included in the firearm-related category, and injuries due to this type of firearm may be less severe.

The injury rates found in this population-based study are lower than those reported in New Mexico. For example, the admission rate per 100 000 in our study was 1.2 and 11.7 for firearms and knives/sharp objects, respectively, compared with 34.3 and 35.1, respectively, in New Mexico.4 This proportion was somewhat different from that reported in Sydney, Australia, where 30% of severe penetrating trauma was due to firearms.15 However, the Australian study reported only patients with an Injury Severity Score of >15, whereas our study included all patients treated at an ED in Ontario.

Limitations

The primary limitation of our data is related to the inability to include data from patients who died without being brought to an ED. These patients are not captured within the NACRS data, thus our results probably underestimate mortality from penetrating trauma. This is likely to differ between guns and knives, with a greater proportion of shooting victims pronounced dead at the scene.

Further limitations are related to the use of administrative data. Although nosologists have standardized practices for coding the data, there is room for misclassification error. Classification of intent is particularly problematic in an ED setting. It is possible that many of the injuries coded as "intent unknown or undetermined" were, in fact, either self-inflicted or inflicted by others. This may differ systematically between men and women, and among the different age groups. In order to try to assess this possibility, we compared the type of injury coded in the ED and in the hospitalization records, to assess the concordance. There was agreement between the ED code and the in-hospital code in 72% of unintentional/intent-unknown cases, 93% of self-inflicted cases, and 94% of assaults.

Conclusions

Analyzing administrative data provides an estimate of the impact of penetrating trauma on a population level, thereby providing prevention programs with data upon which to design their strategies. It is clear that evidence-based prevention strategies are needed to reduce the burden of penetrating trauma. As suggested by other Canadian authors, these strategies may include controlling the import and circulation of firearms, further research, and education.9,10 Monitoring ED and hospitalization data over time will help to assess trends and provide evidence for the effectiveness of such strategies.

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