Road traffic injuries in northern Laos: trends and risk factors of an underreported public health problem

Introduction

Road traffic injures (RTI) are the 8th most common cause of death globally 1. Low- and middle-income countries carry a disproportionate high burden with 91% of the world's fatalities 2. In the western Pacific region, RTI have become the leading cause of death among 15- to 44-year-olds 3.

In Lao People's Democratic Republic (Laos), RTI have dramatically increased with the recent economic development from a low- to a lower middle-income country 4, 5. The majority of its 6.8 million people live in rural areas with underdeveloped infrastructure 4, 5. An annual peak of RTI is seen in April during Lao New Year associated with excessive alcohol consumption 6. With new trans-Asian highway construction, RTI have become the leading cause for hospital admissions in Luang Namtha Province (LNP), northern Laos, in 2006 7. Road safety campaigns in 2007 could temporarily reduce severe RTI by 35% and increase helmet use from 11% to 46%, but no further thereafter 7.

Knowledge of the local situation and common risk factors is essential for effective road safety programmes. Most RTI go unrecorded, and official statistics only reflect part of the problem 8, 9. Some data are already available from the country's capital Vientiane 8-13 but data from rural areas remain scarce. Data validity could be improved if several sources were combined using the capture–recapture method as in other resource-limited settings without reliable surveillance systems 14-18. This method is commonly used to calculate hidden animal populations; a sample is captured, marked and released. In a later sample, the number of marked (‘recaptured’) individuals should be proportional to the marked individuals in the whole population.

The study was conducted to identify characteristics, trends and risk factors associated with RTI in LNP from 2007 to 2010, and to investigate reasons for not wearing helmets. Official police and hospital data were combined to estimate the real RTI incidence.

Methods

Study site

LNPH is a 50-bed hospital which serves the population (149 000 people in 2007) as the referral centre for five district hospitals and the military hospital of the province (Figure 1). It is the only hospital offering X-ray, bone surgery and intensive care for trauma patients 7. CT scan is not available. Seriously injured patients, especially with head trauma, need to be transferred by plane to the capital Vientiane. Around 20 000 outpatients and 3300 inpatients are treated per year 19.

Results

A total of 1080 patients were recruited. Six patients were excluded due to insufficient data. Of the final 1074 patients, 784 (73.0%) were included in the baseline survey, 107 (10.0%), and 183 (17.0%) in the yearly repeated surveys. The majority were young men and VRU (Table 1). Most RTI happened from falls (43.1%) and collisions with vehicles (42.3%). Frequent accident time was in the evening (Figure 2), during weekends (32.7% of 1068) and the month of the Lao New Year celebrations (15.9% of 718 in 2008). Most accidents happened on straight (62.0%), paved (87.7%) and dry roads (92.3%), 50.3% during good weather conditions. A minority of vehicle riders had switched on the lights (28.4% of 1007; 38.4% lights off, 33.2% unknown). Only two farm tractor riders had used lights (31 lights off, 32 unknown).

Reasons for driving without a helmet

A total of 201 patients could be included in the additional survey. Ten patients were excluded because of death (3), unconsciousness (1), no consent (2), no answer regarding helmet use (2) and loss of data (2). Most patients were male (71.6%) and young (median age 22 years, range 14–65). Main reasons for not wearing a helmet were not possessing a helmet and being pillion passenger (Figure 3). Factors associated in multivariate analysis with not wearing a helmet were pillion riding (OR 7.74, 95% CI 3.49–17.2) and alcohol consumption (OR 2.08, 95% CI 1.09–3.97).

Discussion

The study reveals a much higher burden of RTI than officially reported. Most RTI occurred among younger, male and VRU, especially motorcyclists. RTI frequently happened during the evening and Lao New Year. Determinants for serious injuries in motorcyclists were being young, driver and male. Risk factors for more serious head injuries were alcohol consumption, male and no helmet use. Lack of helmet use was determined by pillion riding and alcohol consumption.

Globally, 50% of all deaths are attributed to VRU 4, in the western Pacific, estimates range at 70% 3. In contrast to countries with much higher fatalities among pedestrian such as Bangladesh or India 2, 20, traffic situation and RTI in Laos are more comparable to neighbouring Vietnam, Cambodia and Thailand with similarly high rates of motorcyclists 4, 21-25.

The findings for age and gender are in line with the latest global status report on road safety describing RTI as the leading cause of death among 15- to 29-year-olds worldwide and attributing 3 of 4 road deaths to men 4. In Vietnam, rates of injured male RU ranged from 53% to 64% 18, 79% of deaths occurred among male, and 73% were 15- to 49-year-olds 23. Similar rates are reported from bordering Cambodia and Thailand 4. The age group from 15 to 44 years was calculated carrying a disproportionate burden of 69% of disability-adjusted life years lost from RTI in Thailand 26. Studies have shown that younger drivers have higher motivation towards risky driving due to experience-seeking, excitement and sensation-seeking; on the other hand, increasing driver experience leads to less violation of traffic rules 27.

Most accidents in LNP occurred in the evening, especially between 6 and 7 p.m. Studies from urban areas reported later peaks; in Vientiane, at 8–9 p.m. 9; and in Bangkok, at 9–12 p.m. 28. In rural areas, work traditionally starts earlier, and celebrations and ceremonies in LNP typically take place already at lunchtime. Thus, the strongest effect of alcohol-related RTI could be expected on the way back later in the afternoon/evening. Typical timing of police checks during office hours might have further contributed, presuming that increased police patrols reduce alcohol-related RTI 29. The interdependency between celebrations, alcohol and RTI becomes especially obvious during the festival of Lao New Year in April. Similar findings have been reported during the Thai and international New Year celebrations in Thailand. Driving impairment starts at very low blood alcohol concentration, and the accident risk increases rapidly with rising levels 4, 30-32. The alcohol level was not measured in this study, but yearly consumption of pure alcohol in Laos is estimated to be above the western Pacific average at 7.3 l, especially among males (12.5 l; females: 2.3 l) 32. It is common practice to force each other to empty one's glass during celebrations and ceremonies, regardless of driving 6.

Unfortunately, alcohol advertisements in mass media are increasing, the sale of alcohol is mainly unrestricted, no national action plan exists 6, and the legal alcohol limit of 0.08% lacks implementation 4. Further research is needed to find culturally appropriate ways to target drinking and driving in Laos.

The importance of drugs remains unclear. In contrast to alcohol, drug abuse, including amphetamines, is strongly prohibited and socially unacceptable in Laos. Besides hidden drug use, traditional opium consumption is common in certain minority groups 33 and could be underestimated. However, compared to alcohol, psychoactive drug use contributes far less to RTI in Thailand 34.

The surveys identified male sex, being the driver and young age as important determinants for serious injuries in motorcyclists. These risk factors were also frequently reported from the neighbouring countries Vietnam 18 and Thailand 22, 25, 26, 35. The survey set-up could not include speeding as another contributing factor 36. However, in view of its high association with male sex 36, 37, sex presumably also reflects speeding as a determinant in our calculations. Preventive interventions have to target especially younger male drivers.

The striking rate of unlicensed drivers is much higher than that reported from Thailand 38, 39 and requires further attention in multilevel interventions such as education campaigns, scaling up of driver training and licensing courses, and implementation of existing legislation 40, 41.

The study highlights the importance of helmets for injury prevention in the Lao context. The protectiveness of helmets might be underestimated as the variable ‘helmet use’ did not differentiate for safe buckling. Helmet use is the single most effective way of injury prevention in motorbike riders and can reduce head injuries by 69% and deaths by 42% 42. In Vietnam, helmet law implementation has rapidly decreased road traffic head injuries by 16% and deaths by 18% 43. Our study identified pillion passengers as particularly at risk. Facing a huge lack of helmets in 2007, law enforcement targeted drivers only, but has remained unchanged ever since 7. This unfortunate agreement needs urgent revision. Stricter law enforcement could improve financial priority setting of motorcyclists as decent helmets are available for less than 10 USD, at similar expense as being fined twice. Social marketing of helmets, especially in smaller sizes, could help to equip children and teenagers with good-quality helmets 4.

The interpretation and comparison of injury severity in this study is partly limited by the rather general categories without further differentiation between, for example life-threatening and minor fractures. Furthermore, some patients categorised without obvious injuries may have developed symptoms later. Some deaths on the road may not have been transferred to hospital, leading to selection bias.

Capture–recapture analysis proved to be a valuable method for better RTI estimates. It is limited by some partly unachieved underlying methodological assumptions 44, 45. The common subpopulation was not double-checked, but calculations were based on patients' information regarding police investigations that might have started after the interview, possibly leading to overestimation of RTI. Bias from an unequal likelihood of capture between the two samples might occur with different access to the hospital and the police. Independence of sampling was not investigated, for example by stratification of road users 46, and migration may violate the underlying assumption of a closed population. Further studies may validate this approach in the capital city and other resource-limited settings to better guide policy-making. Underreporting of RTI and deaths remains challenging worldwide. Health data have repeatedly questioned validity and accuracy of official reports. In China, numbers from the official death register were twice as high as police data for 2002–2007 47, 48. In Malawi, the capture–recapture method calculated almost 3–4 times higher fatalities than those extrapolated from police data or hospital-based registries alone 46. In Vietnam, police data accounted for only 22% and hospital data for 60% of the combined estimates of non-fatal RTI for 2000–2004 18. Underestimation originates from structural, methodological and practical limitations, such as lack of national surveillance and reporting systems, and use of different definitions 49, but might also derive from fatalistic beliefs explaining road crashes beyond personal control that demand reconciliation without involving the police 50. The influence of beliefs on RTI prevention has not been well studied in most developing countries including Laos, but might be essential for effective road safety campaigns.

Conclusions and recommendations

This study from northern Laos reveals that RTI disproportionally affects young male road users, especially motorcyclists. Further preventive actions need to target these major risk groups and the typical risk factors of alcohol consumption and lack of helmet use. Law enforcement has to be extended to pillion passengers, to drivers' alcohol consumption, and to licensing. Police should expand traffic checks to after office hours especially during Lao New Year. Alcohol abuse needs further political and societal attention. Further studies are needed to develop effective culturally appropriate interventions for road safety in Laos. RTI in northern Laos remain substantially underreported. Combining existing health and police data systematically within a national registration and surveillance system could help to improve RTI data quality from Laos and similar settings, and help to guide resource allocation in preventive programmes.