Trends and demographic characteristics of physical fighting and fighting-related injuries among Canadian youth, 1993-2010.

Djerboua, Maya ; Chen, Bingshu E. ; Davison, Colleen 等

Physical fighting is a manifestation of interpersonal violence and has become a concerning public health issue worldwide among young people. (1,2) In studies from the United States, nearly one third of adolescents reported participating in at least one physical fight in the previous year. (3-5)

Physical fighting puts adolescents at increased risk for injury. (6-8) Injury is one of the most common reasons for death, hospitalization and disability in young people. (9-11) Fighting is the fifth most common reason for injury in Canadian youth, and the third most common reason for injuries requiring significant medical treatment or overnight hospital admission. Only vehicle- and bicycle-related injuries are more common among young people for medically treated injuries. (9) Due to the potential for harm, it is important for researchers to understand who is at risk for fighting and fighting-related injury, and what reasons or mechanisms underpin these outcomes.

There is limited epidemiological information in a Canadian context that is recent and nationally representative. In Canada there is also minimal information on demographic and socio-economic variation of physical fight involvement and fighting-related injuries. Few studies consider the contextual factors of fighting and fighting-related injuries, such as where the event occurred and who was involved. There is also little information regarding trends that indicate whether physical fights and fighting-related injuries have changed over time. International studies report that physical fighting has decreased over time, although it is difficult to generalize these findings to Canada. (2)

The objectives of this study were to: 1) describe physical fighting and fighting-related injury among Canadian adolescents by sex, grade and subjective social status; and 2) investigate potential trends of physical fighting and fighting-related injuries between 1993-2010 in the overall population and within subgroups.

METHODS

Data sources and sample

This study used Canadian data from the Health Behaviour in School-aged Children (HBSC) study. (6) HBSC is a nationally representative study that was developed in collaboration with the World Health Organization for the purpose of understanding health determinants and behaviours in young people. Canada has collected data every four years since 1998 through questionnaires administered to 11-15 year old students. Six HBSC cycles have been undertaken in Canada during the period 1990-2010. Cycles 2-6 (1993-2010) were used since data for the outcomes of interest were not available for the first cycle. Table 1 includes information about the response rates and sampling strategy for each survey cycle.

The study included a total sample of 61,465 students in grades 6-10. Analysis was undertaken independently for each cycle due to differences in sampling procedures and slight variability in wording and coded responses for each survey item.

Study variables

Physical fighting data were available for cycles 4-6. Participants were asked how many times they were in a physical fight in the previous 12 months. Students who completed this question were categorized as follows: no physical fights, 1 time, 2-3 times, and 4 or more times. A dichotomous variable ("No physical fights" and "One or more physical fights") was created for cross-tabulations.

Fighting-related injury was the second main outcome. Data were available in cycles 2-6. Participants were asked whether they had been injured in the previous 12 months, and the cause of their most serious injury. Responses that said "Yes" to being injured with "Fighting" chosen as the cause were coded as a fighting-related injury.

Data for sex, grade and subjective social status were available in all datasets and used as descriptor subgroups. Participants were asked early in the questionnaire to indicate their sex and grade (response groups: grade <6, grade 7-8 and grade >9). Grade categories correspond roughly with students in primary, middle and secondary schools. Subjective social status was measured by the question "How well off do you think your family is?" with five possible responses, which were then grouped into three categories: high social status ("Very well off", "Well off"), average ("Average"), and low social status ("Not well off", "Not at all well off").

Scenario variables

Variables describing the context of the injury and physical fight encounter included: who the fight was with; whether the injury caused missed school or activities; the type of injury; whether medical treatment was required; the location where the injury occurred; whether the injury happened during an activity or club; the season during which the injury happened; and where treatment was received.

Time trends of physical fighting and fighting-related injury were assessed in terms of differences in overall prevalence and prevalence within subgroups for each one-year time point.

Statistical analysis and survey weights

SAS 9.3 (SAS Inc., Cary, NC) was used for all analyses. Each HBSC cycle had various sampling procedures. In accordance with international protocols, cycles 2-5 were designed to be self-weighted and considered characteristics of the Canadian population for the sampling process. (12,13) Cycle 6 includes survey weights by province and territory within grade groups. Over-represented provinces and territories were given weights of <1, and under-represented groups were given weights of >1. Survey weights ranged from 0.017 to 3.655. (6,11) Prevalence estimates were derived from specific time cycles, and cross-tabulations were performed to obtain frequencies, percentages and prevalence ratios with 95% confidence intervals). The Cochrane-Armitage test for trend was used to establish the significance of increasing or decreasing prevalence trends over time. Ethical approval for this analysis was obtained from the Queen's University Health Sciences Research Ethics Board (File # 6011541).

RESULTS

Distribution of the participants by demographic characteristics and outcomes can be found in Table 2.

Prevalence of physical fighting

The prevalence of physical fighting one or more times ranged from 35.1%-41.2%, and peaked at 41.2% in 2005/2006 (Figure 1). The prevalence from 2001-2010 displays a significant change over time despite the prevalence decrease in 2009/2010 ([p.sub.trend] = 0.015). A significant difference in prevalence from 2001-2010 was also observed in specific groups, including females ([p.sub.trend] < 0.001), grade 7-8 students ([p.sub.trend] = 0.008) and high subjective social status individuals ([p.sub.trend] = 0.002). We do recognize however that further time points are necessary to determine the extent and direction of this trend with certainty.

In demographic subgroups, the prevalence of fighting was higher in males than in females (48.3%-53.4% vs. 23.8%-30.3% respectively) (Table 3). Males were also twice as likely to report a physical fight for each time cycle (p < 0.001).

[FIGURE 1 OMITTED]

As compared to students in grades [greater than or equal to] 9, students in grades <6 had an approximately 20%-30% higher likelihood of reporting a physical fight in the previous year, while grade 7-8 students had 10%-20% increased risk (Table 4). This decrease of physical fight involvement from lower to higher grades was significant within each cycle ([p.sub.trend] < 0.001).

Compared to students from subjectively high social status families, participants who reported low social status were 20%-30% more likely to report a physical fight in the previous 12 months, while those of self-reported average social status had an approximately 10%-15% higher likelihood. Table 4 shows a significant decline in risk from high to low social status groups for all cycles ([p.sub.trend] < 0.001).

Table 5 reports with whom each individual engaged in a fight. Approximately 43% of those who participated in at least one fight reported fighting with a friend or someone they knew, followed by: brother or sister, total stranger, parent or adult family member, and boyfriend, girlfriend or date.

Prevalence of fighting-related injury

Overall fighting-related injury ranged from 1.1%-2.3% (Figure 2). The trend test indicated a significant increase over time in the overall prevalence of fighting-related injury and within all subgroups ([p.sub.trend] < 0.001).

In Table 4, males had 1.5-2.5 fold increased likelihood of reporting a fighting-related injury compared to females (p < 0.05). Individuals in grades <6 had 30%-60% reduced likelihood of reporting a fighting-related injury compared to those in higher grades (Table 4). This association was only significant for 1993/1994, 2001/2002 and 2009/2010. Grade 7-8 participants for most cycles except 2005/2006 had a 24%-40% lower likelihood of reporting a fighting-related injury compared to participants in grades >9. There is an increasing likelihood for fighting-related injury with higher grades in 1993/1994, 2001/2002, and 2009/2010 ([p.sub.trend] < 0.05).

Table 4 shows that for cycles 4-6, those with low subjective social status were 2-3 times significantly more likely to report a fighting-related injury compared to those with high social status. For all cycles except the last, there was a 13%-60% insignificant higher likelihood of fighting-related injury for individuals of average social status compared to those with higher social status. Lower subjective social status was associated with an increased likelihood of reporting a fighting-related injury ([p.sub.trend] < 0.001).

Context of fighting-related injury

Table 6 shows participants who reported a fighting-related injury in the previous 12 months according to the circumstances of the injury. Some questions were not available for all cycles.

For all available cycles, over 50% of those who reported a fighting-related injury missed at least one day of school or activities due to injury.

The three most common results for fighting-related injury were: broken bones, cut or puncture wounds, and bruises or internal bleeding. Broken bones were most common in 1993/1994, and bruises/internal bleeding in 1997/1998 and 2001/2002.

Information on whether the injury needed medical treatment was available in 3 cycles. For 1993/1994, 57.6% of fighting-related injuries required medical treatment. This decreased to 50.2% in 2005/2006 and 46.8% in 2009/2010.

The earliest three cycles stated that most fighting-related injuries occurred in the home or yard, school, and street or parking lot. There is a shift from 2005/2006 onwards where the most common place an injury occurred was the street followed by the school and home.

Determining whether the injury happened during an organized activity or club was possible for the middle three cycles. For all available cycles, 10.1%-26.8% of fighting-related injuries occurred during an organized activity.

Fighting-related injuries most commonly occurred in autumn and second most commonly in summer for the first two cycles, then in spring for 1993/1994 (16%) and in winter for 1997/1998 (14.9%). 2001/2002 presented a different order, where fights most commonly occurred in spring (43.1%), followed by winter (25.7%), autumn (16.5%) and summer (14.7%).

Data pertaining to where the patient was treated were available for 2001/2002 and 2005/2006. Patients were most commonly treated for their injury in emergency rooms, doctors' offices or health clinics.

DISCUSSION

This study shows that physical fighting in children is a relatively common behaviour within Canada (35%-40%), and that obtaining an injury related to fighting (l%-2%) is more rare. Fighting and fighting-related injury prevalence differed significantly over time overall and within specific subgroups. Males are significantly more likely than females to participate in a physical fight and obtain a fighting-related injury. Students in grades six or below were more likely to participate in fights than their older counterparts, while being in a lower grade was protective against fighting-related injury. Individuals from families with subjective low social status were increasingly more likely to obtain both outcomes compared to participants who reported higher subjective social status.

It is possible that because youth are becoming more exposed to violent media, they are also increasingly desensitized to violence and less inhibited when engaging in aggressive activities. (14) Adolescents who are more prone to violent behaviours may have poorer problem-solving skills and coping strategies for solving confrontations, which can result in physical altercations. (15) This is a plausible explanation for the significantly different prevalence estimates over time. It is difficult to determine whether the prevalence of fighting is increasing or decreasing over time due to the unusually high prevalence in 2005/2006. Therefore, more time points are necessary in future research to confidently examine the time patterns of physical fighting. Further research is also needed to explain the biological and sociological mechanisms for these increases. Fighting prevalence changed significantly over time within specific subgroups (females, middle school students, and higher social status students). Since there were slight variations in sampling strategy and the 2009/2010 cycle used weighted data, the trend test results shall be interpreted with caution. Further research is needed to understand why physical fighting over time has altered in these groups.

While physical fighting has altered significantly over time within females, descriptive analyses showed that males were significantly more likely than females to participate in physical fights and obtain a fighting-related injury for all time points. This gendered difference was also reported in previous international studies. (5,6,16) Scientists have postulated biological reasons for the higher prevalence of violent behaviours in males, including the increases of testosterone associated with puberty and increased strength from muscle mass. (17,18) Individuals who reported their families as of lower social status also had an increased likelihood of obtaining both outcomes. This relationship with physical fighting is consistent with previous studies, although we recognize the various ways to define and measure socio-economic status and affluence. (1) However, for the relationship between subjective social status and fighting-related injuries, further analysis accounting for multiple affluence measurements and covariates needs to be done. (19)

Individuals in grades <6 were more likely to participate in fights than their older counterparts. In contrast, however, being in a lower grade was protective against fighting-related injury when compared to higher school levels. These patterns may be because younger adolescents are still developing mentally and physically, and may use physical confrontations to resolve issues. "Play fighting" or "rough-and-tumble play" is a common behaviour among younger people and these behaviours decrease as students approach adulthood. (20) Concurrently, adolescents also undergo physiological changes such as increased muscle mass and hormonal changes during puberty. The elevated strength in older adolescents may intensify the physical force exerted in fights, which can increase the likelihood of injury. (17,21) The way grade school and high school students interpret situations may vary, where the circumstances and consequences behind physical confrontations may become more severe as adolescents get older; as a result, there may be more intent to harm. (22)

Findings associated with the context of fighting and fighting-related injuries showed that the person participants most frequently fought with was "a friend or someone I know" or a sibling. This is logical since adolescents habitually interact with these people. The next most popular response was "other". There is no information that describes the remaining possible options for this category. It is postulated that the "other" category can represent rivals that the students know sufficiently well to warrant their not being a stranger, but not enough to be "friends". Future surveys should present the option to describe who the "other" person is.

From 1993-2002, the most common places that a fighting-related injury occurred were in a home or yard and at school. Adolescents spend the majority of their time at home and school, which makes the increased likelihood of obtaining a fighting-related injury more plausible. Information was only available for one cycle (1993/1994) with regard to whether the injury occurred during or outside of school hours. This data would be useful for assessing the context of fighting-related injuries, particularly in relation to differentiating physical bullying or domestic violence. From 2005 onwards, the most common response for where the injury took place shifted from the home to the street. It is unknown why there is a shift in location over time.

Earlier cycles (1993-1998) suggest that fighting-related injuries most commonly occur during the fall, followed by summer. This could be because adolescents return to school and are more likely to go outside during these seasons, which allows for more physical interactions. In 2001/2002, fighting-related injuries were most common during the spring, another time when young people engage in more outdoor activities. It is unclear why there is this seasonal shift for this cycle only.

Data suggest that many of the reported injuries are serious enough to require medical attention. The fact that most of these injuries tend to happen outside of activities or clubs suggests that these outcomes may be associated with levels of supervision. A potential solution could be increased student involvement in supervised activities.

Strengths and limitations

Strengths of this study include that this research uses nationally representative data. This supports its generalizability to the Canadian adolescent population. The large sample size in each cycle also provides substantial power to detect significant differences between subgroups. The results from this study can help identify vulnerable groups and contextual factors that may pose risk, and establish priority areas for preventing physical fights and additional injury risk.

This study also contains important limitations. First, the self-reported nature of the data may present potential misclassification for both the exposures and outcomes due to the subjectivity and interpretation of each variable. For example, asking how "well off" somebody is may be a measure of subjective social status, as we have suggested, however it could also be a measure of family income or material wealth. As there is no availability of current validation studies with Canadian students for this question, the exact interpretation is not known. In addition, fighting-related injury can be misclassified as sports-related if an injury occurred because of a fight during a sport or martial arts. This indicates that not all fighting-related injuries are being captured.

Students who were absent on the day of the survey due to injury or suspension for engaging in a fight may not have been selected to participate. Furthermore, the study does not consider adolescents who dropped out of school. These individuals may be fundamentally different in how well off they are and their experiences with violence compared to students still enrolled in school. These can indicate selection bias. (2)

There were also inconsistencies in the collection of data for some variables across HBSC cycles, particularly with respect to the context of the injury, injury severity and care received. This limited our ability to assess some variables for potential confounding or effect modification. Furthermore, the limited number of data points for the trend analysis makes it difficult to assess whether the pattern was linear or exponential. More data points would be informative for trend interpretation.

A last limitation is that the survey only asks participants about the circumstances of their most serious injury. If fighting was not the cause of their most serious injury, data will be truncated. Other less serious fighting injuries may be masked in some circumstances and therefore under-reported in the sample.

CONCLUSION

Physical fighting among young Canadians has become a public health issue of greater concern in the past two decades. Specific subgroups have a higher propensity for physical fight participation and sustaining an injury from these encounters. Understanding the context of these conflicts and injuries can be informative for reducing future occurrences.

REFERENCES

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Received: August 25, 2015

Accepted: March 25, 2016

Maya Djerboua, MSc, [1] Bingshu E. Chen, PhD, [1] Colleen Davison, PhD [1-3]

Author Affiliations

[1.] Department of Public Health Sciences, Queen's University, Kingston, ON

[2.] Clinical Research Centre, Kingston General Hospital, Kingston, ON

[3.] Department of Emergency Medicine, Queen's University, Kingston, ON Correspondence: Colleen Davison, PhD, Department of Public Health Sciences, Queens University, 62 Fifth Field Company Lane, Kingston, ON K7L 3N6, Tel: 613533-6000, ext. 79518, E-mail: davisonc@queensu.ca

Acknowledgements: This study was funded by research grants from the Public Health Agency of Canada (PHAC) (contract 4500307663) and the Canadian Institutes of Health Research Team in Child and Youth Injury Prevention. MD was supported by the Empire Life Child Health Research Fellowship and the Queen's Graduate Award. The Canadian version of the Health Behaviour in School-aged Children (HBSC) study is a part of the international collaborative study developed in collaboration with the World Health Organization. The Canadian HBSC Study was funded by PHAC and Health Canada.

Conflict of Interest: None to declare. Table 1. Dataset details for the Health Behaviour in School-aged Children study cycles from 1993-2010 Student School-level HBSC Sample response response cycle size rate rate 1993-1994 7020 Not available Not available 1997-1998 11,415 Not available Not available 2001-2002 7235 7235/9780 = 74% 172/231 = 74.5% 2005-2006 9717 9707/13,176 = 73.7% 186/248 = 75% 2009-2010 26,078 26,078/33,868 = 77% 436/765 = 57% Province/ HBSC territory Description of sampling approach cycle response rate 1993-1994 Not available Systematic cluster sampling, with replacement. All non-private school jurisdictions with students in grades 6, 8 and 10 in a Canadian province or territory were identified. These grades were chosen to correspond to the international study age group targets of 11, 13 and 15 year-olds. A representative sample of schools with students at these levels was generated considering student grade, school enrolment size, community size, location in province or territory, language of instruction and public/Catholic jurisdiction. School administrators of the chosen schools were asked to randomly choose one whole class in each of the targeted grades (if they had them) to participate. Under the international protocol prescribing no weighting of data sets, to be nationally representative, the sample was designed to approximately proportionally represent number of students by grade in each of the provinces and territories. 1997-1998 12/12 = 100% Same as 1993, however a grade-by-grade sample of grades 6-10 was used instead of limiting the dataset to only grades 6, 8 and 10. 2001-2002 10/13 = 76.9% Same as 1997. 2005-2006 12/13 = 92.3% Same as 1997. 2009-2010 11/13 = 84.6% Same as 1997, except an attempt at a census for all northern schools was made and an increase in overall sample size was facilitated to allow for reporting at the provincial/territorial level, as well as national reporting. Student data were weighted according to provincial/territorial enrolments to ensure these were nationally representative when national reports were being made. Table 2. Characteristics of the participants in the Health Behaviour in School-aged Children study from 1993-2010 HBSC cycle 1993-1994 * 1997-1998 * Overall N = 7020 N = 11,415 ([dagger]) ([dagger]) Descriptors Age (mean 13.5 [+ or -] 1.7 13.8 [+ or -] 1.6 [+ or -] SD) n (%) n (%) Sex Male 3350 (47.9) 5500 (48.4) Female 3644 (52.1) 5870 (51.6) Grade [less than or 2329 (33.2) 2137 (18.7) equal to] 6 7-8 2356 (33.5) 4296 (37.7) [greater than or 2335 (33.3) 4967 (43.6) equal to] 9 Subjective social status Low 923 (13.2) 1562 (13.9) Average 2931 (42.0) 4890 (43.5) High 2574 (36.9) 4784 (42.6) Unknown 549 (7.9) -- -- Total 6977 (100) 11,236 (100) Missing 43 179 Outcomes Physical fighting None -- -- -- -- 1 time 2-3 times 4 or more times Total Missing Fighting-related injury No injury 4371 (63.3) 6962 (63.6) Yes 92 (1.3) 119 (1.1) No, injury not 2442 (35.4) 3870 (35.3) related to fighting Total 6905 (100) 10,951 (100) Missing 115 464 HBSC cycle 2001-2002 2005-2006 Overall N = 7235 N = 9717 ([dagger]) ([dagger]) Descriptors Age (mean 13.6 [+ or -] 1.5 14.0 [+ or -] 1.5 [+ or -] SD) n (%) n (%) Sex Male 3357 (46.4) 4604 (47.4) Female 3878 (53.6) 5111 (52.6) Grade [less than or 2063 (28.5) 1723 (17.7) equal to] 6 7-8 2788 (38.5) 3670 (37.8) [greater than or 2384 (33.0) 4324 (44.5) equal to] 9 Subjective social status Low 597 (8.9) 808 (8.6) Average 2315 (34.3) 3003 (32.0) High 3826 (56.8) 5585 (59.4) Unknown -- -- -- -- Total 6738 (100) 9396 (100) Missing 497 321 Outcomes Physical fighting None 4542 (65.0) 5652 (58.8) 1 time 1192 (17.0) 1705 (17.7) 2-3 times 787 (11.2) 1372 (14.3) 4 or more times 472 (6.8) 885 (9.2) Total 6993 (100) 9614 (100) Missing 242 103 Fighting-related injury No injury 3574 (52.0) 5364 (56.0) Yes 116 (1.7) 216 (2.2) No, injury not 3184 (46.3) 4001 (41.8) related to fighting Total 6874 (100) 9581 (100) Missing 361 136 HBSC cycle 2009-2010 Overall N = 26,078 ([dagger]) Descriptors Age (mean 13.8 [+ or -] 1.6 [+ or -] SD) n (%) Sex Male 12,815 (49.2) Female 13,254 (50.8) Grade [less than or 5165 (19.8) equal to] 6 7-8 10,471 (40.2) [greater than or 10,442 (40.0) equal to] 9 Subjective social status Low 2339 (9.5) Average 8276 (33.6) High 13,998 (56.9) Unknown -- -- Total 24,613 (100) Missing 1466 Outcomes Physical fighting None 16,203 (64.4) 1 time 4092 (16.3) 2-3 times 3067 (12.2) 4 or more times 1786 (7.1) Total 25,148 (100) Missing 930 Fighting-related injury No injury 12,959 (51.6) Yes 543 (2.1) No, injury not 11,632 (46.3) related to fighting Total 25,134 (100) Missing 944 * No physical fighting variables from HBSC 1993-1994 and 1997-1998. ([dagger]) Variable totals may not equal sample size because of missing data for some variables. Table 3. Prevalence of physical fighting (one or more times) and fighting-related injury for each HBSC cycle (1993-2010) overall and by demographic characteristic (sex, grade and subjective social status);trend analysis across HBSC time cycles also reported Physical fight (1 or Physical fight (1 or more times) n(%) more times) n(%) [P.sub. trend] HBSC cycle 2001-2002 2005-2006 2009-2010 ([dagger]) Variable Sex Male 1552 (48.3) 2421 (53.4) 5944 (48.7) 0.167 Female 899 (23.8) 1541 (30.3) 2997 (23.2) 0.001 Grade [less than or 733 (37.7) 819 (48.1) 1992 (40.9) 0.275 equal to] 6 7-8 984 (36.3) 1612 (44.3) 3652 (36.4) 0.008 [greater than 734 (31.4) 1531 (35.8) 3300 (32.3) 0.335 or equal to] 9 Subjective social status Low 239 (40.4) 414 (51.3) 964 (42.3) 0.452 Average 850 (36.9) 1299 (43.5) 3073 (37.9) 0.367 High 1272 (33.4) 2132 (38.4) 4504 (32.8) 0.002 Overall * 2451 (35.1) 3962 (41.2) 8945 (35.6) 0.015 Fighting-related Fighting-related injury n(%) injury n(%) HBSC cycle 1993-1994 1997-1998 2001-2002 2005-2006 Variable Sex Male 57 (1.7) 74 (1.4) 64 (2.0) 149 (3.3) Female 34 (0.9) 44 (0.8) 52 (1.4) 67(1.3) Grade [less than or 17 (0.7) 14 (0.7) 24 (1.2) 32 (1.9) equal to] 6 7-8 28 (1.2) 48 (1.2) 43 (1.6) 106 (2.9) [greater than 47 (2.0) 57 (1.2) 49 (2.1) 78 (1.8) or equal to] 9 Subjective social status Low 11 (1.2) 20 (1.3) 17 (3.0) 41 (5.1) Average 41 (1.4) 55 (1.2) 44 (2.0) 68 (2.3) High 32 (1.3) 42 (0.9) 52 (1.4) 102 (1.8) Overall * 92 (1.3) 119 (1.1) 116 (1.7) 216 (2.3) Fighting-related injury n(%) HBSC cycle 2009-2010 [P.sub. trend] ([dagger]) Variable Sex Male 360 (2.9) <0.001 Female 183 (1.4) <0.001 Grade [less than or 87 (1.8) <0.001 equal to] 6 7-8 196 (1.9) <0.001 [greater than 260 (2.6) <0.001 or equal to] 9 Subjective social status Low 91 (4.0) <0.001 Average 210 (2.6) <0.001 High 223 (1.6) 0.001 Overall * 543 (2.2) <0.001 Note: No physical fighting variables from HBSC 1993- 1994 and 1997-1998. * Overall n and % calculated from total HBSC population for that cycle. ([dagger]) Cochrane-Armitage test for trend for physical fighting and fighting-related injury across HBSC time cycles. 2001-2010 for physical fighting, and 1993-2010 for fighting-related injuries. Table 4. Prevalence ratios and 95% confidence intervals for the outcomes of physical fighting and fighting-related injury by demographic characteristics across HBSC cycles, 1993-2010 Physical fighting (1 or more times) prevalence ratio (95% Cl) HBSC cycle 2001-2002 2005-2006 Variable Sex Male 2.03 (1.90-2.17) 1.76 (1.67-1.85) Female Ref. Ref. p-Value <0.001 <0.001 Grade [greater than 1.20 (1.10-1.30) 1.34 (1.26-1.43) or equal to] 6 7-8 1.16 (1.07-1.25) 1.24 (1.17-1.31) [greater than Ref. Ref. Ref. or equal to] 9 p-Trend <0.001 <0.001 <0.001 Subjective social status Low 1.21 (1.09-1.35) 1.34 (1.24-1.44) Average 1.10 (1.03-1.18) 1.13 (1.08-1.20) High Ref. Ref. p-Trend <0.001 <0.001 Physical fighting (1 or more times) prevalence ratio (95% Cl) HBSC cycle 2009-2010 1993-1994 Variable Sex Male 2.10 (2.03-2.18) 1.84 (1.20-2.80) Female Ref. Ref. p-Value <0.001 0.004 Grade [greater than 1.27 (1.21-1.32) 0.37 (0.21-0.63) or equal to] 6 7-8 1.13 (1.09-1.17) 0.60 (0.38-0.95) [greater than Ref. or equal to] 9 p-Trend 0.001 Subjective social status Low 1.29 (1.22-1.36) 0.96 (0.49-1.90) Average 1.16 (1.12-1.20) 1.13 (0.72-1.79) High Ref. Ref. p-Trend <0.001 0.913 Physical fighting Fighting-related (1 or more times) injury prevalence prevalence ratio (95% Cl) ratio (95% Cl) HBSC cycle 1997-1998 2001-2002 Variable Sex Male 1.82 (1.26-2.64) 1.45 (1.01-2.08) Female Ref. Ref. p-Value 0.001 0.044 Grade [greater than 0.58 (0.33-1.04) 0.58 (0.36-0.94) or equal to] 6 7-8 0.98 (0.67-1.44) 0.76 (0.51-1.14) [greater than Ref. Ref. or equal to] 9 p-Trend 0.116 0.023 Subjective social status Low 1.47 (0.87-2.50) 2.12 (1.23-3.64) Average 1.28 (0.86-1.91) 1.41 (0.95-2.10) High Ref. Ref. p-Trend 0.117 0.005 Fighting-related injury prevalence ratio (95% Cl) HBSC cycle 2005-2006 2009-2010 Variable Sex Male 2.50 (1.88-3.33) 2.08 (1.75-2.49) Female Ref. Ref. p-Value <0.001 <0.001 Grade [greater than 1.04 (0.69-1.56) 0.68 (0.54-0.87) or equal to] 6 7-8 1.60 (1.20-2.14) 0.76 (0.63-0.91) [greater than Ref. Ref. or equal to] 9 p-Trend 0.261 <0.001 Subjective social status Low 2.78 (1.95-3.96) 2.43 (1.91-3.09) Average 1.24 (0.91-1.68) 1.59 (1.32-1.91) High Ref. Ref. p-Trend <0.001 <0.001 * No physical fighting variables from HBSC 1993-1994 and 1997-1998. Table 5. Reports of physical fighting (one or more times) by with whom they fought from the Canadian HBSC Survey, 2001-2006 Physical fighting (1 or more times) across HBSC cycles 2001-2002 2005-2006 (N = 7235) (N = 9717) n (%) n (%) Overall 2451 (35.1) 3962 (41.2) Who did you fight with? Total stranger 222 (9.7) 272 (7.1) Parent or adult 30 (1.3) 100 (2.6) family member Brother or sister 515 (22.4) 1101 (28.6) Boyfriend, 47 (2.0) 71 (1.8) girlfriend or date A friend or 987 (42.9) 1666 (43.3) someone I know Other 499 (21.7) 637 (16.6) Total 2300 3847 Missing 151 115 Note: "Who did you fight with" variable is not included in the 2009-2010 HBSC Survey. Table 6. Reports of injuries related to fighting by variables describing the scenario from the Canadian HBSC Survey, 1993-2010 Fighting-related Fighting-related injuries injuries across HBSC cycles across HBSC cycles 1993-1994 1997-1998 Variable n (col%) n (col%) Injury caused missed day 51 (55.4) 68 (57.1) of school or activities Results of injury Broken bone 33 (36.6) 18 (15.6) Sprain/strain 7 (7.8) 7 (6.1) Cut or puncture 20 (22.2) 10 (8.7) wound Concussion or 6 (6.7) 9 (7.8) head/neck injury Bruises or 16 (17.8) 44 (38.3) internal bleeding Burns 0 (0) 6 (5.2) Internal injury -- -- -- - (operation) Other 8 (8.9) 21 (18.3) Total 90 115 Missing 135 464 Injury needed 53 (57.6) -- -- medical treatment Place that injury occurred Home/yard 28 (31.1) 50 (42.0) School 23 (25.6) 30 (25.2) Sports arena/facility 7 (7.8) 10 (8.4) Street/parking lot 13 (14.4) 14 (11.8) Park 6 (6.7) -- -- Commercial/business area - -- -- -- Other 13 (14.4) 15 (12.6) Total 90 119 Missing 136 514 Injury happened during - -- 12 (10.1) activity, league or club Season that injury occurred Winter 11 (13.6) 17 (14.9) Spring 13 (16.0) 16 (14.0) Summer 28 (34.6) 35 (30.7) Fall 29 (35.8) 46 (40.4) Total 81 114 Missing 365 647 Place treated for most serious injury Doctor's office/ -- -- -- -- health clinic Emergency room Hospital admission overnight School health services Other Total Missing Fighting-related Fighting-related injuries injuries across HBSC cycles across HBSC cycles 2001-2002 2005-2006 Variable n (col%) n (col%) Injury caused missed day 59 (51.8) 116 (57.1) of school or activities Results of injury Broken bone 16 (13.8) -- -- Sprain/strain 10 (8.6) Cut or puncture 14 (12.1) wound Concussion or 7 (6.0) head/neck injury Bruises or 32 (27.6) internal bleeding Burns 29 (25.0) Internal injury 5 (4.3) (operation) Other 3 (2.6) Total 116 Missing 692 Injury needed -- -- 103 (50.2) medical treatment Place that injury occurred Home/yard 42 (38.9) 43 (20.5) School 26 (24.0) 50 (23.8) Sports arena/facility 7 (6.5) 23 (11.0) Street/parking lot 23 (21.3) 62 (29.5) Park -- -- -- -- Commercial/business area 3 (2.8) -- -- Other 7 (6.5) 32 (15.2) Total 108 210 Missing 533 148 Injury happened during 13 (11.4) 55 (26.8) activity, league or club Season that injury occurred Winter 28 (25.7) -- -- Spring 47 (43.1) Summer 16 (14.7) Fall 18 (16.5) Total 109 Missing 858 Place treated for most serious injury Doctor's office/ 30 (30.9) 47 (24.8) health clinic Emergency room 33 (34.0) 43 (22.8) Hospital admission 9 (9.3) 25 (13.2) overnight School health services 7 (7.2) 6 (3.2) Other 18 (18.6) 68 (36.0) Total 97 189 Missing 898 379 Fighting-related injuries across HBSC cycles 2009-2010 Variable n (col%) Injury caused missed day 311 (61.5) of school or activities Results of injury Broken bone -- -- Sprain/strain Cut or puncture wound Concussion or head/neck injury Bruises or internal bleeding Burns Internal injury (operation) Other Total Missing Injury needed 245 (46.8) medical treatment Place that injury occurred Home/yard 93 (18.5) School 127 (25.3) Sports arena/facility 43 (8.6) Street/parking lot 142 (28.2) Park -- -- Commercial/business area -- -- Other 98 (19.4) Total 503 Missing 1334 Injury happened during -- -- activity, league or club Season that injury occurred Winter -- -- Spring Summer Fall Total Missing Place treated for most serious injury Doctor's office/ -- -- health clinic Emergency room Hospital admission overnight School health services Other Total Missing Figure 1. Prevalence of physical fighting (one or more times) over time (2001-2010). Overall [p.sub.trend] = 0.015 HBSC Cycle (Year) Prevalence (%) 2001-2002 35.1 2005-2006 41.2 2009-2010 35.6 Note: Table made from line graph. Figure 2. Prevalence of fighting-related injuries over time 1993-2010). Overall [p.sub.trend] < 0.001 HBSC Cycle (Year) Prevalence (%) 1993-1994 1.3 1997-1998 1.1 2001-2002 1.7 2005-2006 2.3 2009-2010 2.2 Note: Table made from line graph.