Sot. S-i. Med. Vol. 30. No. 5. pp. 639440. !990 Printed in Great Bntain. All rights reserved

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0277-9536:90 53.00 + 0.00 c 1990 Pergamon Press plc

RESEARCH NOTE DRIVING EXPERIENCE AND THE RISK OF TRAFFIC ACCIDENT AMONG MOTORCYCLISTS TZE-WAI

WONG,‘*

JAMES LEE,’ WAI-ON

PHOON,’PO-CHU YIU,~ KAM-PUIFUNGI and

JACK A. MCLEAN’ ‘Department of Community and Family Medicine, The Chinese University of Hong Kong. Shatin. New Territories, Hong Kong, *Department of Community, Occupational and Family Medicine, National University of Singapore, Kent Ridge, Singapore, 3National Institute of Occupational Health and Safety, Sydney, Australia, ‘Department of Paediatrics, National University of Singapore, Kent Ridge, Singapore and 5Road Accident Research Unit, The University of Adelaide, Adelaide, SA 5001, Australia Abstract-In a case+zontrol study on the risk of traffic accidents among motorcyclists in Singapore. we demonstrated an inverse monotonic relationship between accident risk and driving experience. As compared to drivers with less that I yr of driving experience, the odds ratios (adjusted for race, age and frequency of riding) for those with driving experience of l-4, 5-9 and IO yr or more were 0.60,0.50 and 0.36, respectively. We propose that intensive in-circuit training of learner motorcyclists should replace the conventional on-the-road training on the basis that the former serves to increase their driving experience without subjecting the learner motorcyclists to the risk of sustaining road accident. Key words-traffic

accident, motorcyclist, driving experience, Singapore

INTRODIJCIION

Motorcycle accidents are an important contributing factor to morbidity and mortality especially among the younger age group [l]. Injuries sustained during such accidents are often severe because of the lack of an enclosed protection for the motorcyclist. Driving a motorcycle requires a higher degree of skill than driving a motor care [2]. For example, a motorcyclist has to control both the front-wheel and rear-wheel braking system separately. Steering and balancing are demanding skills for the motorcyclist. To evaluate the role of driving experience as a risk factor in traffic accident, we conducted a case-control study of injured motorcyclists. Our hypothesis was that a more experienced motorcyclist has better control of the motorcycle and is less likely to sustain a road traffic accident. METHOD

From April 1986 to June 1987, motorcyclists who were injured in traffic accidents and admitted to Singapore General Hospital were interviewed for personal data (age, sex and ethnicity), driving experience and frequency of use of the motorcycle. Driving experience was defined as the time period when the motorcyclist used his motorcycle as a mode of transport regardless of the status of the licence. This includes the period when the motorcyclist commuted with a provisional driving licence. It is a fairly *Address correspondence to: Dr Tze-wai Wong. Department of Community & Family Medicine, The Chinese University of Hong Kong, 4/Floor, Lek Yuen Health Centre. Shatin, New Territories, Hong Kong.

common practice among motorcyclists in Singapore to use a provisional Iicence as a defacro full licence, with no intention of taking a driving test. Frequency of driving was categorized into ‘frequent’ (driving a motorcycle for 3 or more days per week) and ‘infrequent’ (less than 3 days a week). As a control or comparison group, the same information was sought from motorcyclists who were never involved in accidents leading to hospitalization. The control subjects were obtained from the neighbourhood of the cases based on a list of a registration of motorcycle licensees. The association between driving experience and accident risk was evaluated by the odds ratios obtained by multiple logistic regression analysis [3], in which the case-control status was taken as the response variable while the primary exposure variable (driving experience) and potential confounding variables (frequency of riding, age and ethnicity) were entered as regressor variables. Analysis of driving experience was in terms of binary variables based on the following 4 categories: driving experience of less than I, l-4,5-9 and IO yr and above. Exponentiating the regression coefficient of a particular regressor variable yielded the odds ratio for that variable, statistically adjusted for the confounding effects of all other variables in the model. Female motorcyclists and those belonging to ethnic groups other than Chinese, Malays and Indians were too few and were excluded from the study. RESULTS A total of 193 cases and 178 controls were interviewed. The mean age for cases was 29.6yr with a standard deviation of 10.7yr. Controls had a mean age of 30.0 yr with a standard deviation of 9.9 yr. The

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Table I. Ethnic distribution of cases and controls Ethnicity

Cases (%)

Controls (%)

Chinese Malay Indian All

106 (54.9) 73 (37.8) I4 (7.3) 193 (100)

93 (52.2) 63 (35.4) 22(12.4) 178 (100)

ethnic distribution of cases and controls are compared in Table 1. There were more Chinese and Malays but fewer Indians in cases than in controls. Table 2 presents the odds ratios at different levels of driving experience for accident risk statistically adjusted for age, ethnicity and frequency of riding. The odds ratios decrease with increasing driving experience. As compared to the drivers with less than I yr of experience, those with 10 yr or more of experience had an odds ratio of 0.36, with an upper 95% confidence limit of 0.89. Odds ratios for 5-9 and l-4 yr were 0.5 and 0.6 respectively. However, their upper 95% confidence limits exceed unity. The frequency of driving a motorcycle as a risk factor was adjusted for driving experience, age and ethnicity. The odds ratio for frequent riders was 1.79, as compared to infrequent riders, with a 95% confidence interval of 0.95-3.37.

they learn basic skills in handling the motorcycle. Only after they pass the driving test would they be allowed to drive on the road. In this study, we have shown that the driving experience of a motorcyclist is inversely associated with traffic accident risk. This is in accordance with the assumption that a person with longer driving experience should have better control of his vehicle and hence be able to avoid the occurrence of an accident. The rationale for in-circuit training for motorcyclists, now implemented in several countries, is similar. Driving experience is gained through training before the learner motorcyclists are exposed to the risk of road accident. The incidence of accidents among motorcyclists trained in this setting was found to be low (Traffic Police Department, Singapore, unpublished data). This study is limited to hospitalized motorcyclists who survived the accident. Neither were those involved in accident without injury included. Hence only part of the entire spectrum of motorcyclist accident victims were included. Despite the limitation of the study, we propose that more vigorous training, to improve the driving skill of the motorcyclist, should be implemented to reduce the incidence of motorcycle accident which have reached epidemic proportions in many developed and developing countries.

DISCUSSION

Training programmes for learner motorcyclists has received much attention in many countries [4]. In Singapore, learner motorcyclists have been phased out of on-the-road learning. Previously, a person who had applied for a learner licence was allowed to drive a motorcycle on the road with an L-plate. They are now required to undergo training in a circuit where Table 2. Odds ratio for different levels of driving experience Driving experience (yr) Cl l-4 5-9 2 IO

Odds ratios* (95% confidence limit) 1.00 0.60 0.50 0.36

*Statistically adjusted for age, ethnicity

(0.30-1.17) (0.24-1.06) (0. M-0.89)

and frequency of riding.

study was supported by a grant from the World Health Organization. We would like to thank the Ministry of Health and the Traffic Police Department of Singapore for their assistance. Acknowledgements-This

REFERENCES

Khoo C. K. Yearbook of Slafisrics. Department of Statistics, Singapore, 1988. McLean A. J.. Brewer N. D.. Hall C. T.. Sandow B. L. and Tamblym P. J. Adelaide In-depth Accident Study. 1975-1979 The University of Adelaide, 1979. Breslow N. E. and Day N. E. Starislical Merhods in Cancer Research. Vol. I. The Analysis of Case-Control Studies. IARC (Publication No. 32). Lyong, 1980. Newlands G. Motorcycling morbidity and mortalityan unstudied epidemic. S. Afi. med. J. 64, 155-158. 1983.

Driving experience and the risk of traffic accident among motorcyclists.

In a case-control study on the risk of traffic accidents among motorcyclists in Singapore, we demonstrated an inverse monotonic relationship between a...
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