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Pattern of injuries in helmeted motorcyclists in Singapore
  1. K-Y Tham1,
  2. E Seow1,
  3. G Lau2
  1. 1Department of Emergency Medicine, Tan Tock Seng Hospital, Singapore
  2. 2Centre for Forensic Medicine, Health Sciences Authority, Singapore
  1. Correspondence to:
 Dr K-Y Tham
 Department of Emergency Medicine, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433, Republic of Singapore; kum_ying_thamttsh.com.sg

Abstract

Background: Singapore has a mandatory helmet law for motorcyclists. This study aimed to determine the injuries sustained by helmeted motorcyclists presenting to the emergency Department (ED).

Methods: Adult victims of motor vehicular incidents (MVI) who presented to an urban public hospital ED from 1 December 1998 to 31 May 1999 were interviewed. Chart reviews were done for those hospitalised. Data collected were demographic, nature of injury, ambulance care, ED and hospital care, outcome and final diagnoses.

Results: Motorcyclists formed 49.1% (1018) of all MVI victims, of whom 96.1% were men. The mean age was 32.5 years (SD 13.1), significantly younger (p<0.0001) than the mean age of 36.4 years (SD 16.4) among other MVI victims. The proportions of motorcyclists and other MVI patients admitted to the hospital were not different. Among those admitted, significantly fewer (p = 0.001) motorcyclists (32.2%) sustained head injury compared with other MVI victims (46.8%) but among the motorcyclists with head injury, more than one third (34.2%) had severe head injury. The proportion of patients with thoracic injury was not different (p = 0.93) between motorcyclists (10.2%) and other MVI victims (9.9%). However, among those with thoracic injury, 79.2% of motorcyclists had severe thoracic injury, significantly more (p = 0.04) than 50% of other MVI patients. Wounds, fractures, and/or dislocations of the limbs (p<0.001) were significantly more among motorcyclists compared with other MVI patients.

Conclusion: Compared with other MVI victims, fewer helmeted motorcyclists sustained head injury. When head injury occurs in helmeted motorcyclists, it tends to be more severe. Motorcyclists remain vulnerable to extremity injury and to severe chest injury.

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In 1998 there were 370 804 cars and 133 375 motorcycles and scooters registered1 in Singapore, a city state with a resident population of 3.86 million. With a limited land area of 648.1 km2, the Singapore government encourages use of its well developed public transport system and discourages car ownership by making it very expensive. Therefore, unlike countries in which motorcycle use is associated with recreation and leisure,2,3 it is an important means of daily transportation for a significant number of people in Singapore. For this group of people, motorcycle ownership and use is less expensive than car ownership and still gives them independence from public transport. For comparison, in a number of Asian nations,4 the number of motorcycles are in the order of millions and formed more than 50% of total number of vehicles.5 For example, Malaysia has a population of about 20 million with 3.7 million motorcycles forming 56% of total number of vehicles, Taiwan has a population of 22 million with 11.9 million motorcycles forming 74% of total number of vehicles, and Thailand has a population of 60.2 million with 8.2 million motorcycles forming 65% of total number of vehicles. Clearly the motorcycle is an important means of daily transportation for these and many similar nations.

Many studies6–19 have been done comparing patterns of injuries between helmeted and non-helmeted motorcyclists. These studies concluded that helmets protected the motorcyclists by reducing the frequency and severity of head injuries. In Singapore it is mandatory for motorcyclists and their pillion riders to wear helmets when riding their vehicles. This law was passed in 1972 and has been strictly enforced. Compliance by Singaporeans and foreigners is close to 100%. However, motorcyclists still accounted for most road casualties in Singapore. The Traffic Police Department reported that in 1998, 222 persons died and 7412 persons were injured in motor vehicle accidents (MVI), of which motorcyclists accounted for 87 (39.2%) of those killed and 3641 (49.1%) of the injured.1 It seems that helmets protect the motorcyclists and change the pattern of fatal and non-fatal injuries but do not necessarily affect the number of accidents involving motorcyclists. This study was undertaken to determine the pattern of injuries sustained by helmeted motorcyclists in Singapore as they presented to the emergency department (ED).

METHODS

The study was conducted in a 1000 bed acute urban public hospital in which the annual census of the ED was 110 000. From 1 December 1998 to 31 May 1999, all consecutive patients above 15 years old with MVI injuries who presented to the ED were enrolled in the study. Interviews with the patients or suitable surrogates were conducted in the ED using a closed-ended questionnaire. All the ED doctors were briefed on the use of the questionnaire. The doctor who provided care for the patient also administered the interview. Because of the logistic problems posed by the large number of patients involved, we did not attempt to have a second observer counter check the data captured during the interviews. The computerised 24 hour ED attendance log was checked to ensure enrolment of all eligible patients. A trained research nurse extracted data of those patients who were not interviewed during their episode of ED care.

For patients who were admitted to the hospital, chart reviews were also done by the first (KYT) and second (ES) authors. Again, because of the large number of patients involved, we did not attempt to have a second observer counter check the data collected during the chart review. The following data were collected: (1) demographics, (2) ambulance timings, (3) cause and nature of injury, (4) assessment of physiological parameters in ED, (5) ED care and in-hospital care, (6) definitive anatomical injury diagnoses upon discharge or death obtained from charts, radiology reports, or necropsies, and (7) outcomes—that is, survival or death at discharge from the hospital and length of stay in the intensive care unit (ICU).

The revised trauma score (RTS)20 and the abbreviated injury scale 1990 version (AIS-90)21 were used to characterise injury severity. The injury severity score (ISS)22 was calculated based on the AIS-90. The RTS and ISS were then used to perform TRISS analysis as described by Boyd et al23 to determine the probability of survival (Ps) for the group of patients who met one or more of the following criteria: (a) died from their injuries, (b) admitted to high dependency (HD) unit ICU, or (c) ISS 16 or higher. This group was designated the major trauma subset. Two sets of blunt trauma coefficients were used in the TRISS analysis: (1) US24 coefficients for blunt trauma where b0 = −1.2470, b1 = 0.9544, b2 = −0.0768, b3 = −1.9052 and (2) Scottish25 coefficients where b0 = 0.945, b1 = 0.642, b2 = −0.122, b3 = −1.886. Ordinal data were analysed by χ2 test and continuous data by Student’s t test. Where appropriate a p value equal to or less than 0.05 is considered significant. Statistical calculations were performed with the Statistical Package for Social Sciences (SPSS) (Chicago, USA).

This study was approved by the hospital ethics committee.

RESULTS

The total ED attendance for the six months of the study period was 52 680 of which 11 313 (21.5%) were for trauma related complaints. Among these 11 313 patients, there were 1018 (9%) motorcyclists, 1057 (9.3%) other MVI victims, and 9238 (81.7%) non-MVI trauma victims. The 1018 motorcyclists formed 1.9% of total ED patient load and 49.1% of all MVI victims. Among the other MVI victims, there were 401 (37.9%) pedestrians, 246 (23.3%) car drivers, 248 (23.5%) vehicle passengers, and 162 (15.3%) cyclists. The mean age of the motorcyclists was 32.5 years (SD 13.1), which was significantly lower (p<0.0001) than 36.4 years (SD 16.2) for other MVI patients. An overwhelming majority (96.1%) of motorcyclists were men compared with a significantly lower (p<0.0001) proportion of 60.9% men among other MVI patients. Motorcyclists sustained injuries from skidding in 46.5%, collision with a car in 35.2%, collision with a heavy vehicle in 7.3%, and collision with other objects in 11%.

The ethnic group distribution in the general population in 19981 was 77% Chinese, 14% Malay, 7.6% Indian, and 1.4% others. Among motorcyclists seen in the ED, there were 65.3% Chinese, 20.8% Malay, 11.8% Indian, and 2.2% other ethnic groups, with the proportions of Malay and Indian being significantly higher (p<0.0001). In addition to the resident population, there are 20 000 foreign workers from West Malaysia, a neighbouring country that is 25 km north of Singapore. Most of these Malaysian foreign workers commute daily on motorcycles and scooters to work in Singapore. This group of foreign workers formed 16.7% of the injured motorcyclists seen in the ED.

About half (51.5%) of the motorcyclists were brought to the ED by the emergency ambulance service, which was comparable to 54.2% of other MVI victims brought in by the emergency ambulance service. A history of alcohol consumption before sustaining injury or the presence of alcohol on the patient’s breath was classified as clinically detectable recent alcohol consumption. The proportion of motorcyclists with clinically detectable recent alcohol consumption was 0.9%, which was not significantly different from the 0.9% among other MVI victims. Four motorcyclists and five other MVI victims sustained traumatic arrest en route to the ED and died in the ED. The proportion of motorcyclists admitted to the hospital was 23.2%, which was not significantly different from the 21% of other MVI victims. Table 1 summarises the demographic characteristics of the motorcyclists and other MVI patients. Figure 1 showed the outcome of all MVI patients.

Table 1

 Demographic characteristics of motorcyclists and other MVI patients

Figure 1

 Outcome of all MVI patients.

Among those discharged from the ED, the patterns of principal injuries sustained by the motorcyclists and other MVI victims are summarised in table 2. Minor wounds to the head and trunk occurred in 56% of the other MVI patients but only in 24.3% of motorcyclists (p<0.001). However, abrasions, wounds, and fractures of the limbs are much more common among the motorcyclists discharged from the ED. The proportion of minor head injury and other injury is not significantly different between the two groups. Upon discharge from the ED, half (49.9%) of the motorcyclists did not need any follow up, 25.1% were referred to the orthopaedic outpatient clinic, and 22.8% were referred to their primary care physicians. For the other MVI patients, 63.6% did not need follow up, 19.2% were referred to their primary care physicians, and only 12.5% needed orthopaedic outpatient review. Motorcyclists needed longer sick leave after discharge from the ED.

Table 2

 Injuries sustained and follow up plans for motorcyclists and other MVI patients discharged from the ED

For each patient admitted to the hospital, the AIS regions with the three most severe injuries were recorded. Table 3 summarises the proportion of motorcyclists and other MVI patients who sustained injuries to each of the six AIS regions. Excluding AIS region six external system, 28.8% of motorcyclists sustained injuries to two or more regions, which is not significantly different from 23% of other MVI patients. The proportion of other MVI patients with head and neck injuries was significantly higher (p = 0.001) than that among motorcyclists. However, among motorcyclists with head injury, 34.2% sustained severe head injury (defined by AIS ⩾3), significantly more (p = 0.02) than 19.2% among other MVI patients. Only five (6.6%) motorcyclists and 14 (13.4%) other MVI patients sustained injuries to the neck or cervical spine among those with head and neck injuries. The overall number with thoracic injuries was not significantly different between the two groups but motorcyclists had almost twice the number of severe thoracic injuries compared with other MVI patients. This finding is somewhat reversed for abdominal and pelvic content injuries in which other MVI victims had more with severe injuries compared with motorcyclists. Similar to patients discharged from ED, a significantly higher (p<0.0001) proportion of hospitalised motorcyclists (66.5%) sustained extremities and pelvic girdle injuries compared with other MVI patients (40.5%).

Table 3

 Injuries sustained by motorcyclists and other MVI patients admitted into hospital

Motorcyclists and other MVI patients who met the major trauma subset criteria24,25 were further examined. Table 4 shows the demographic characteristics, physiological parameters, in-hospital management, RTS, ISS, and probability of survival (Ps) of this subset of patients. There were 28 motorcyclists and 28 other MVI patients who met the major trauma definition. Table 4 showed that the characteristics and parameters of both groups were not significantly different except for the mean age and the proportion of men.

Table 4

 Comparison of motorcyclists and other MVI patients in the major trauma subset

DISCUSSION

According to the Singapore census of population for year 2000,26 4.8% of the population rides the motorcycle as the mode of transport to work. The typical motorcyclist comes from a lower income household, lives in a public flat, and is a blue collar worker or a less skilled white collar worker.26 Our study also found that motorcyclists were younger, almost exclusively male, and many more were Malays. This profile does not differ greatly from an earlier study by Wong et al27 of hospitalised motorcyclists from 1986 to 1987. However, one major difference is the apparent reduction in alcohol use, from the 10% reported by Wong et al and 2.3%–3% reported by Chao et al28 for 1987 to 1989, to 0.9% in our study. Comparison of alcohol use among the three studies is limited by different sampling methods: Wong et al calculated the rate based on historical report, Chao et al used blood alcohol concentrations, and this study used patient’s report and the ED doctor’s observation of alcohol on patient’s breath, which was at best a subjective assessment. Aside from differences in sampling methods and study populations, the Singapore Traffic Police has implemented vigorous drunk driving control measures through public education and random breath testing in the past decade. We believed this had resulted in the small number of drunk MVI victims in our study. Unlike reports by other researchers,7,29,30 alcohol use is not a major cause of motorcycle crashes in Singapore now and this is supported by a report from the National Safety Council of Singapore in the local newspaper,31 which states that dangerous riding habits resulting in loss of control of the vehicle and not being alert to traffic conditions are the primary causes of most accidents.

Clinical studies7–9,11 and epidemiological studies6,10,12–19 by other researchers who compared helmeted with non-helmeted motorcyclists consistently found a strong protective effect of helmets against head injury. With the mandatory helmet law in force for almost 30 years, Singapore researchers have little baseline data to compare injury patterns sustained by non-helmeted motorcyclists. Despite such comprehensive helmet laws, motorcyclists and their pillion riders still form the largest group of road fatalities annually in Singapore, ranging from 43.2% in 19981 to 54.7% in 2000. For comparison, in nations where helmet laws were either absent or not enforced, motorcyclists typically formed more than 50% of road fatalities,5 for example, motorcyclists formed 54% of road fatalities in Taiwan and 63.4% in Thailand. In this study, the proportion of motorcyclists with head injury was lower than other MVI patients, indicating the strong protective effect of helmets. However, among the motorcyclists with head injury, the proportion with serious head injury was higher than the other MVI patients. This seems to imply that there is a limit to the protection by helmets against head injury beyond which other factors, for example, crash characteristics, will affect severity of head injury even in helmeted motorcyclists. This has important bearings on public health and education in that safe riding habits and behaviour must be promoted together with helmet use to see a reduction in the number of motorcycle casualties.

Where the helmet law has been successful in changing the pattern of head injury among motorcyclists, they remain vulnerable to extremity injuries. Wounds and fractures of the limbs have resulted in many more motorcyclists requiring follow up care with either primary healthcare givers or at the orthopaedic outpatient clinic, resulting in higher health resources utilisation. Being younger and within their economically active years, the longer sick leave resulting from injuries translates into economic loss for the motorcyclists and for the society.

Motorcyclists are also vulnerable to severe thoracic injury. The proportion of motorcyclists with thoracic injury is not significantly different from other MVI victims but the proportion with severe thoracic injury is very much higher among motorcyclists. Although the abdomen like the thorax is equally exposed to injury, interestingly, the proportion of severe abdominal injury among motorcyclists was much lower than other MVI patients. More work will need to be done to understand motorcycle crash characteristics to explain the difference in injury patterns between the thorax and the abdomen. Possibly because of the small number of patients who met the major trauma definition, comparison between motorcyclists and other MVI victims did not yield any additional significant differences.

One of the limitations of the study was the lack of data for the group of road fatalities who died at scene and were not sent to the ED. While it remained possible that the pattern of injuries for this group might have been different, we believed however that the injuries seen among our major trauma subset approximated those who died at scene. Another limitation was that the study centre had the highest number of trauma patients in the entire nation. This could lead to findings of higher proportion of MVI victims and higher proportion of serious injuries than what really existed in the nation. Finally, because of the large number of patients involved, we could not arrange for a second observer to obtain data, resulting in a single observer study with all its inherent potential weaknesses.

In summary, compared with other MVI victims, fewer helmeted motorcyclists sustained head injury. When head injury occurs in helmeted motorcyclists, it tends to be more severe. Motorcyclists remain vulnerable to extremity injury and to severe chest injury even though the same is not observed for abdominal injury. Though helmet laws have been in place in Singapore for a long time, more can be done to reduce the heavy fatality toll among motorcyclists, especially by promotion of safe riding behaviour.

Acknowledgments

We thank Ms Anisa, A Quek, Rahimah and staff of the emergency department for their help with the data and Mr S P Chan for his help with the statistical analysis.

REFERENCES

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Footnotes

  • Funding: this study was supported in part by a grant from Tan Tock Seng Hospital, Singapore.

  • Conflicts of interest: none declared.

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