Distribution of transport injury and related risk behaviours in a large national cohort of Thai adults
Karen Stephan Matthew Kelly Rod Mcclure Sam-ang Seubsman Vasoontara Yiengprugsawan Christopher Bain Adrian Sleigh
▶ 8.4% of Thai adults reported a transport related injury in the previous 12 months. ▶ Risk was higher for males and young adults and motorcycles were commonly involved. ▶ Males were much more likely to report drink driving than ...
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PubMed Central (PMC)
3.2. Distribution and frequency of transport injury

Overall 7279 (8.4% or 8354 per 100,000) of cohort respondents reported a transport-related injury as their most serious injury. In all age groups, males reported more transport injury than females. Young adults were more likely to report transport injury than older adults ( ). There was little difference in the proportion who reported transport injury between country residents (8.6%) and city/town residents (8.1%).

explores the roles the injured respondents played on the occasion of their transport-related injury. Of the 6371 injured persons who reported their role, there were 4514 (70.9%) drivers, 1459 (22.9%) passengers and 398 (6.2%) pedestrians. In all age groups, a higher proportion of injured males were likely to be drivers compared to injured females, with the reverse being true for passengers. A higher proportion of females (7.2%) experiencing transport-related injury were pedestrians compared to males (5.4%) and this injury category was the only one with a notable age-effect, with the proportion of injured that were pedestrians increasing with age for both sexes, reaching 15.6% among women over 50.

Among the injured, 71.9% were riding motorcycles when their transport injury occurred ( ). This proportion decreased in older age groups but motorcycles were still the most common vehicle involved in transport injury events in all age groups in both sexes (70.8% for men, 73.2% for women). The proportion injured in cars or buses and vans increased with age for both sexes while the proportion injured while riding bicycles decreased with age for men but not for women. Injuries sustained while a driver or passenger in other types of vehicles (e.g. train, boat or airplane) were uncommon.

3.3. Prevalence and distribution of transport-related risk behaviours

The distribution of transport-related risk behaviours was determined for the whole cohort, in order to better target interventions. Of the respondents who reported using a motorbike, approximately 6% of males and 10% of females rarely or never wore a helmet ( ). Overall, females were less likely to wear a helmet than males, with the highest proportion of non-wearers being women over 50 years of age (18.9%).

Of the respondents who had a front seat belt available for use in the vehicle, 72.2% of males and 66.6% of females reported always wearing the front seat belt and this increased with age ( ). Teenagers had the highest proportion of respondents who reported never wearing a front seatbelt (10% of males, 9% of females).

In contrast, back seat belt use was low ( ). Of those who said the vehicle had a back seat belt available, over 50% of males and 65% of females never wore it, although as age increased there was a reduction in the proportion who never wore back seat belts. For all age-groups, men were more likely than women to sometimes or always wear the back seat belt.

Male drivers were much more likely to report having driven after 3 or more glasses of alcohol in the previous 12 months than female drivers (56.1% compared to 17.2%; ). This comparison excluded respondents who said that they never drank alcohol (39.0% of females and 10.5% of males in the cohort).

4.1. Transport Injury

In this study, 8.4% (8354 per 100,000) of the cohort reported that their most serious injury was transport-related, with males and teenagers more likely to be injured and motorcycles the most common vehicle involved. The proportion of injured who were pedestrians increased with age.

As anticipated, the transport injury rates were substantially higher than previously reported for Thailand. Estimates of 152 and 650 per 100,000 population were reported from the Thai Ministry of Public Health (Wibulpolprasert, 2008) and the community-based Thai National Injury Survey, respectively (Sitthi-amorn et al., 2007). The overall patterns of factors surrounding the transport injury, however, are similar with the young and males being the most at risk, motorcycles being the most common vehicle involved and the risk of being injured as a pedestrian increasing with age.

Both previous population surveys used higher injury severity thresholds than our study. The Ministry of Public Health data captured hospitalised injuries (Wibulpolprasert, 2008), while the National Injury Survey captured injuries requiring three or more days off work and/or medical attention (Sitthi-amorn et al., 2007). Further, the National Injury Survey relied on the head of the house reporting for all members, compared with our study which involved self-report. Because our TCS included minor injuries and the respondent reported on their own injuries, we would expect our injury estimates to be higher. Very minor injuries may still have been overlooked as respondents may not recall less serious injuries that occurred during the previous 12 months. In addition, we missed capturing data on transport injuries that were not the most serious injury that the respondent sustained. Thus our estimate is probably conservative.

The external validity of the study in terms of extrapolating the results to the Thai adult population is difficult to judge. Our cohort has slightly more females, less young (<21) and older (>40) adults and is more educated than the Thai adult population. Considering that young males are at higher risk of injury, and our cohort includes proportionally less of these than the Thai population, the estimates may be conservative. However, we also have proportionally less older adults, which may serve to increase the transport injury estimates. The higher education level of the respondents may also lead to a decreased injury rate relative to the general population. It is important to note however, that we are reporting the baseline data for an ongoing cohort study, so the real strength in these data lies in the internal validity for monitoring changes in this cohort over time.

4.2. Transport-related risk behaviours

The cohort reported a much higher prevalence of the use of safety devices (motorcycle helmets and seat belts) than previously reported for Thailand in the World Health Organization (WHO) Global Status Report on Road Safety (WHO, 2009). Almost two-thirds of motorcycle users (65%) reported always wearing a helmet compared to 27% in 2005. This rate is lower than for other Southeast Asian middle-income countries with similar legislation, e.g. Malaysia and Indonesia, that reported helmet-wearing rates of 90% or more in 2007 (WHO, 2009). Since helmet wearing was made mandatory in Thailand, however, enforcement has been maintained (WHO, 2009) and may be starting to have the desired cumulative effect. The lower helmet use rate reported by females was notable and could reflect concern with hair-style or hygiene but we did not gather data on motives.

Over two-thirds of respondents (69%) reported always using a front seat belt compared to 56% in 2005. This is similar to Malaysia in 2003, where the seat belt wearing rate was 70%, but less than Indonesia in 2005 when the rate was 85% (WHO, 2009). Only 11% reported always using a back seat belt, however this was still more than previous estimates (3% in 2005; WHO, 2009). There is substantial room for improvement if the Thai population is to reach the wearing rates evident in many of the high income countries (e.g. Australia, New Zealand and Germany in 2006/2007) of 95% or more for front seat belts and 87% or more for back seat belts (WHO, 2009). Considerable benefit would be achieved by mandating seat belt wearing for all vehicle occupants, rather than just front seat occupants as at present.

Excluding respondents that reported never drinking alcohol, more than half of the male drivers (56.1%) reported driving after three or more glasses of alcohol compared to 17.2% of female drivers. The high prevalence of drink driving among male Thai drivers has been reported previously with a cross-sectional study of blood alcohol (BAC) content in 4778 Thai drivers finding 8.7% with a blood alcohol content greater than 50 mg/dl (Chongsuvivatwong et al., 1999). Females were excluded from their analysis, however, because they only made up 2% of the sample. To our knowledge, ours is the first study to highlight the differences between men and women in terms of driving under the influence of alcohol in Thailand. Considering that female respondents in our cohort were much more likely to report never drinking at all (39.0% compared to 10% of males), and those that did drink alcohol were much less likely to drink drive than male drivers, it appears that drink driving countermeasures should be targeted heavily towards male drivers.

Our estimates of the prevalence of transport-related risk behaviours may be biased due to the self-report nature of data collection. Respondents may fail to report behaviours that are risky or socially unacceptable, however, many of our respondents did report drink driving or never wearing seat belts so this does not appear to be a major issue. The lower proportion of young adults aged under 21 and higher education level of our cohort compared to the Thai population may explain the higher estimates for helmet wearing and seat belt wearing than have been found previously. Consequently, the prevalence of the use of safety devices reported in this study probably represents the most optimistic estimates of current safety practices in Thailand. It is, however, unclear what effect this might have on the generalisability of estimates of the prevalence of drink driving. Again, however, we must emphasise the value of our data in terms of the internal validity for monitoring changes in this cohort over time.