A profile of bicycle-related injuries in Tai Po

Hong Kong Journal of Emergency Medicine A profile of bicycle-related injuries in Tai Po LLY Lee, KL Yeung, JTS Chan, RCI Chen Background: Implementation of prevention programs for bicycle safety should be based on a good understanding of the profile of bicycle accidents. The objective of this study was to investigate the differences in the severity of bicycle-related injuries when comparing with various risk factors, and to utilize this information to formulate the intervention measures. Methods: A retrospective review was conducted on all patients (n=116) who were treated for bicycle-related injuries within a period of 66 days at the emergency department of a district hospital in Tai Po, New Territories. Results: School-aged children, especially boys, were more commonly injured. The head and lower extremities were the common sites of injuries. Female gender (χ 2 =4.39; P<0.05) and injuries involving head and upper extremities (χ 2 =12.61; P<0.05) were associated with higher chance of serious injury. Conclusion: Tai Po district had a high incidence of bicycle accidents due to its geographical location. Population at a greater risk for bicycle injury was the male gender school-aged children and therefore prevention program should be targeted at them. (Hong Kong j. emerg.med. 2003;10:81-87) Keywords: Bicycling, head protective devices, incidence, traffic accidents, wounds and injuries Introduction The first concept of bicycle was the draisienne or hobbyhorse invented by a German called Baron von Drais in 1818. It was almost completely made of wood and the rider propelled it by pushing their feet against the ground like the Flintstone's cars. Bicycle was modified by various persons in the 19th and 20th centuries and was developed into a style that we see nowadays since the 1930's. 1-4 Bicycle is a universally accepted form of transportation, recreation, sport and exercise tool. Correspondence to: Lee Lap Yip, Larry, BSc(Med), MBBS(UNSW), MRCSEd Alice Ho Miu Ling Nethersole Hospital, Accident and Emergency Department, 11 Chuen On Road, Tai Po, N.T., Hong Kong Email: leelyl@hotmail.com Yeung Kwai Lin, RN, RM, BSN Chan Tak Shing, Jimmy, FHKAM(Surgery), FHKAM(Emergency Medicine) Chen Chung I, Raymond, FHKAM(Community Medicine), FHKCCM, MHP Consequently, bicycle-related injuries are common and account for a substantial proportion of injuryrelated morbidity especially in children. Among those child victims, head injuries are the commonest cause of fatalities. 5-9 Prevention programs had generally been focused on bicycle-related head injuries of children in the past few decades including the use of bicycle helmet. The idea of triage was first practiced in all emergency departments under Hong Kong Hospital Authority in 1992. There are five categories (1-5) that patients will be triaged according to their complaints, anatomical and physiological parameters. 10 These five categories are used to prioritize consultations in regard to the severity of illness. Unfortunately, sometimes the true pictures of the patients cannot be detected by the current triage system. The objectives of this study were to provide baseline information about bicycle-related injuries occurring in Tai Po district and to analyse whether there was any difference in the severity of injury by age, gender

82 Hong Kong j. emerg. med. Vol. 10(2) Apr 2003 and injury patterns. It was hoped that detected differences, together with the baseline information, could predict the types of persons prone to a greater risk of bicycle injury. This would enable us to suggest appropriate priorities for intervention and prevention. Subjects and methods Study area The setting of this study was in Alice Ho Miu Ling Nethersole Hospital, a 500-bed district hospital established in 1997 and 24 hours emergency service was available since April 1, 1998. It serves a population of around 0.3 million in Tai Po district. Tai Po is formerly a fishing village and situated in the eastern part of the New Territories and is relatively close to the rural area when compared with the other hospitals in this territory. The bicycle trails along Tolo Harbour, Ting Kok Road and Tai Mei Tuk are hot cycling spots. Consequently, hiring bicycles for leisure is a very popular form of entertainment for people travelling to Tai Po during weekends and public holidays. Together with those who ride bicycles for transportation and exercise, there is a much higher incidence of bicycle accidents when compared with other districts. According to government statistics, there were around 300 cases of bicycle accidents reported per year in the past few years. 11 However, the official data always underestimated the true figures of bicycle accidents, especially the minor ones. 12 Patients All bicycle accident cases presenting to the emergency department between September 28, 2000 and December 3, 2000 were included in this study for retrospective review. Information was collected on demographic data, triage categories, waiting time, injury patterns, distribution of injuries and medical consequences. The sources of the information included the accident and emergency case notes, computerbased patient records and in-patient medical records. For those patients who were admitted into hospital, their in-patient records were traced and the types of treatments were recorded. Being a district hospital, some services were not available and those patients would be transferred to a higher centre and their medical consequences were also traced by using the computer system in the Hospital Authority intranet. Statistical analysis The spread of the patients' waiting time against the severity of injuries was described by a box-and-whisker plot and was further analysed by the Kruskal-Wallis test to see any significant differences between the groups. The Spearman's rank correlation coefficient was also calculated in order to demonstrate any correlation between the spreading of the waiting time. Chi-squared tests were employed to investigate any association between the severity of the injury and various factors such as gender, age groups and distribution of injuries. The above information was evaluated by the Statistical Package for Social Science SPSS version 10.0. Results Demographic data One hundred and sixteen patients were seen in the emergency department due to bicycle-related injuries during the study period. Male outnumbered female victims by nearly a factor of two (62% and 38% respectively). The mean age of the recruited patients was 25 years and the range was from 2 to 87 years old. The mean ages of both genders were 27 years in male and 22 years in female. The recruited patients were divided into three age groups for analysis: primary school children or below (11 years old or below), secondary school children (12 years old-17 years old) and adults (18 years old or above). We found that 53 (45.7%) of them were in school age or below. The proportions of both genders in each age group were described as segmented columns in Figure 1. There were fewer female victims in both the secondary school and adult age groups but the proportion was equal in the primary school age group. Distribution of injuries (Figure 2) More than half of the patients suffered from injuries in the extremities (n=63; 54.3%). Among those 63 patients, lower extremities were commoner sites to be

Lee et al./bicycle injuries in Tai Po 83 Figure 1. Age distribution segmented by gender. Figure 2. Distribution of injuries. involved compared with the upper extremities. Eleven (17.5%) of them had either fractures or dislocations and among these, fractures of leg and elbow were predominant. Thirty-four patients (29.3%) presented with head and face injuries that was the second commonest site of injury just after lower extremities injuries. Six patients were transferred to other hospitals for further management due to skull fractures, concussion or amnesia. There were only eight patients presenting with injuries in the trunk region and one of them had fracture of lumbar spine. Mixed type injuries represented those patients who suffered from injuries in multiple sites with similar severity. A total of 11 patients belonged to this category. Mechanism of injuries Majority of them were injured as a result of fall from bicycles (98; 84.5%). Other mechanisms of injuries including being hit by bicycles and trapping of feet by rear wheels represented 12.9% (n=15) of the injured cyclists. Only three patients (2.6%) were involved in collisions with motor vehicles. Medical consequences Among those 116 patients, half of them (58; 50%) received only non-invasive interventions in the emergency department such as dressing, oral analgesia, splintage and strapping and 14 patients (12.1%) received no treatment at all during their stay in the emergency department. Invasive procedures like suturing and closed reduction were performed in 24 patients (20.7%). Lastly, 20 patients (17.2%) required admission or transfer to other hospitals and four of them had operations performed during their hospital stay. Types of injuries Simple abrasions and contusion accounted for 69.8% of injuries and 14% of them had lacerations that required suturing. Fractures of any kind accounted for another 14% and there were two elbow dislocations. Waiting time and severity of injuries A box-and-whisker plot was attached (Figure 3) to demonstrate the spread of waiting time against the severity of injuries expressed in an ordinal format. This distribution of waiting time stratified by the severity of injuries was further analyzed by the Kruskal-Wallis test that showed a statistically significant difference there. (P<0.05; df=3). Risk factors and severity of injuries The risk factors including age group, gender, holiday cyclists and distribution of injuries were compared with the severity of injuries. To do this, the total study population was classified as either severe (C and D in Figure 3) or non-severe (A and B in Figure 3) and the chi-squared tests were used to analyse the data.

84 Hong Kong j. emerg. med. Vol. 10(2) Apr 2003 Figure 3. A box-and-whisker plot of the spread of waiting time (in minutes) vs severity of injury. Analysis with 2x2 tables showed that there was no significant difference in severity with regard to both age groups and holiday cyclists (χ 2 =1.82; P=0.40 and χ 2 =0.01; P=0.92). (Table 1) Referring to the table, the proportion of female cyclists who injured severely was more than two times the male and significant differences between the two groups were demonstrated statistically. (χ 2 =4.37; P<0.05). Head injuries were well accepted to be the leading cause of morbidity and mortality including cerebral contusion, skull fracture, and postconcussional symptoms. This was also reflected in this study. Together with the upper extremities, both groups were associated with a higher rate of more severe injuries. (χ 2 =12.61; P<0.05) Discussion With regards to the government publication, the total number of injured as a consequence of bicycle accidents in Tai Po district ranged from 283 to 363 in 1999 and 2001 respectively. 11 The data supplied was obviously underestimated because there were already 116 cases recorded in this 66 days study period. By simple calculation, around 600 cases of bicycle accidents are expected in one year. Furthermore, the actual number of injuries due to bicycle accidents may be even higher, as a considerable proportion of the injured do not seek for emergency services. Compared with the whole territory, the Tai Po district was responsible for nearly a quarter of all bicycle accidents according to government statistics. This reflected the fact that this district had a much higher incidence of bicycle accidents. On the other hand, injuries that led to fatal outcomes were hardly seen here, unlike the western countries. Previous studies showed that most fatalities occurred in cyclists who were involved in collisions with motor vehicles. 6-8 Only a relatively low number of collisions with motor vehicles (only 2.6%) were reported in this district. This phenomenon could be explained by good city planning with well-designed bicycle trails that were separated from the main traffic in this district. Not surprisingly, school-age children were the most frequent victims of bicycle accidents particularly the male but no association could be demonstrated between them and more serious injuries. Generally speaking, cyclists of school age were expected to have a higher risk of severe injury according to previous statistics. 7 The reason why the same findings could

Lee et al./bicycle injuries in Tai Po 85 Table 1. Distribution of injury severity in variables Severity Non-severe Severe Total (1) Age group 0-11 23 9 32 12-17 12 9 21 >17 37 26 63 Chi-squared=1.822, P=0.402 (2) Holiday Rider Yes 40 24 64 No 32 20 52 Chi-squared=0.011, P=0.915 (3) Gender Male 50 22 72 Female 22 22 44 Chi-squared=4.386, P=0.036 (4) Distribution of injury Head & face 16 18 34 Trunk 4 4 8 Upper extremities 14 13 27 Lower extremities 28 8 36 Mixed 10 1 11 Chi-squared=12.625, P=0.013 not be observed in this study might be due to the dilution effect of school age victims who only had minor injuries but were brought to the emergency department by their anxious caregivers. In addition, the road traffic ordinance Chapter 374 Section 54 stated that no person shall hire a bicycle to a child under 11 years of age or permit a child under 11 years of age to ride a bicycle unaccompanied by an adult. This ordinance could further reduce the rate of serious injuries in primary school children. In this study, there were fewer female victims but they were shown to have a higher chance of suffering from more severe injuries as a result of bicycle accidents. One Sweden study found that there was a lower incidence of bicycle accidents in females but older females were more likely to be seriously injured. 13 The reason why females were associated with more severe injuries could hardly be explained. Relatively worse bicycle skills when compared with male might be the reason. Triage system was widely used in the past decade in order to correctly prioritize consultations with regard to patients' complaints, anatomical and physiological parameters. Applying this concept to bicycle-related injuries, ideally, there should be a negative linear relationship between the waiting time and the severity of injury. This expected relationship was proved in this study but there was only a small variance (7%). This was because the spread of the waiting time was very narrow and the mean value of waiting time ranged

86 Hong Kong j. emerg. med. Vol. 10(2) Apr 2003 only from 6.8 minutes to 12.6 minutes. Anyway, the result was somehow encouraging because the effectiveness of the present triage and risk management system was further confirmed. The benefit was not only in patients with life-threatening conditions, but also in stable patients with relatively serious injuries. Head injuries and upper extremity fractures were the common reasons for hospitalization as a result of bicycle injury. 6,9 These injuries tended to be more severe because these parts were relatively more delicate and fragile when compared with other body regions. Moreover, these were commonly the initial parts of the body landing on the ground after a fall from bicycle and absorbing most of the forces. The incidence of bicycle-related injuries and the resulting morbidity and mortality has enormous economic implications in terms of provision of medical service and loss of working hours. The question up to this stage is how to minimize the number of bicycle accidents in our society. Common strategies to prevent these injuries are the use of bicycle helmet and safety instructions. The use of helmets has been a hot topic in the past two decades and the rationale of its use is twofold. Firstly, previous studies had proved its effectiveness in reducing both the incidence and severity of bicycle-related injuries. 14-16 Secondly, bicycle-related head injuries accounted for a substantial proportion of emergency department attendance and bicycle-related fatalities. 6,9,17,18 However, barriers to promote helmet use were unpredictably enormous 19,20 and difficulty was encountered particularly in low-income class schoolboys. 21,22 The promotion of helmet use requires both community-based and school-based efforts. Trials of community-based programs, school-based interventions and subsidy to purchase bicycle helmets were shown to be effective in some way but the benefits of the programs were not evenly distributed. 15,16,21,23-33 The prevalence of bicycle helmet use was low despite of researches proving its effectiveness. 5,7,20 More significant results in promoting the use of bicycle helmets were achieved by legislation in the mandatory use of bicycle helmet like in Australia and New Zealand. However, a drop in the number of cyclists was recorded after the legislation and this suggested the greatest effect of the helmet law was not to encourage cyclists to wear helmets, but to discourage cycling instead. 34-37 Moreover, maintenance of the increased rate of helmet use required regular education and law enforcement by the police. In addition to the promotion of bicycle helmet use, efforts should be made on other areas. These include bicycle skill training, education about road safety and law, road engineering to alert cyclists in doing turns at intersections and proper instruction to bicycle renter. In a nutshell, bicycle-related injury was a major but preventable component of traumatic morbidities. Preventive program was obviously a necessity in our society especially in a district that had the highest incidence of bicycle accidents. Conclusion Tai Po district, due to geographical reasons, had a higher incidence of bicycle accidents when compared with other districts. In this study, we found that boys within school age were the most frequent victims but female cyclists were associated with more serious injuries. Head and extremities injuries were the leading causes of morbidities and protective devices for those parts were important. Only a small proportion of bicycle accidents occurred as a result of collisions with motor vehicles and therefore fatal injury was rarely seen and a well-designed bicycle trail network in this district might explain this. Since bicycle-related morbidities and mortalities are significant and preventable, preventive program is crucial especially the promotion of bicycle helmet use. References 1. Bicycle history. www.cycle-info.bpaj.or.jp/english/ learn/chistory.html. Accessed on 28 February 2003. 2. Bicycle history. www.otal.umd.edu/~vg/amst205.s97/ vj29/vg/history.html. Accessed on 28 February 2003. 3. The Bicycle Museum of America. www.bicyclemuseum.

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