Escalating Global Road Traffic Injuries and the Global Burden of Disease Initiative

Good data now exist to show that rapidly urbanizing and motorizing low-income and middle-income countries (as defined by The World Bank) are experiencing an epidemic of road traffic injuries that pose a major public health hazard to residents and tourists. (1)

View of busy road in India. Source: http://www.abc.net.au/reslib/200706/r155206_559607.jpg; accessed February 24, 2008.

View of roads in Nakuru, Kenya, Africa. Source: http://www3.iclei.org/la21/ascn/nakuru1.jpg; accessed February 24, 2008.

A road traffic injury, according to one of many definitions, involves

"a road user, a vehicle and the built environment as elements of a dynamic system that work together to either produce or prevent injuries. Road users include drivers or occupants of buses, trucks and passenger cars, riders on motorized two-wheelers (MTWs), cyclists and pedestrians. Pedestrians, cyclists, bus passengers and MTW riders are called vulnerable road users because they are at greater risk of injury or death if involved in a collision. Vehicles can be either motorized (cars, trucks, two- and three-wheelers) or non-motorized (bicycles, carts, rickshaws). The road environment varies by road location (rural or urban), type of road (motorway or street), time of day, visibility and traffic flow". (2)

Organized concern by world banking and public health organizations with mortality and disability from road traffic injuries began in earnest in the late 1980s and early 1990s.

I. The World Bank Initiates Global Disease Burden Measurement

In the 1980s, The World Bank, whose mission is to reduce global poverty in low- and middle-income countries, became interested in quantifying "the net gain in health or reduction in disease [and injury] burden from a health intervention in relation to the cost" of that intervention. (3) The World Bank wanted to implement an ongoing "cost-effectiveness" measure that quantified "the loss of health life from disease measured in disability-adjusted life years". The World Bank named this measure of dollars per Disability Adjusted Life Year the DALY.

It is not surprising that a bank would want to know this information to guide allocation of its assets. The World Bank partnered with the World Health Organization, which partnered with Harvard School of Public Health (HSPH, principals: Christopher Murray and Alan D. Lopez) in the early 1990s to collect and synthesize DALY data from participating member states of the World Health Organization. (4,5) From the perspective of the public health sector, whose mission is to promote the general health of people, the DALY measure quantifies global burden of disease (GBD).

The World Bank and WHO jointly defined the DALY as "a unit used for measuring both the global burden of disease and the effectiveness of health interventions, as indicated by reductions in the disease burden. It is calculated as the present value of the future years of disability-free life that are lost as the result of premature deaths or cases of disability occurring in a particular year." (3)

Individual WHO member states have benefited from the DALY measurement system. For example, public health researchers in Malaysia noted in their presentation at a 2005 Mumbai, India, conference the following:

"The growing demand for health services under limited resources poses a challenge for governments to respond to peoples health needs wisely. Inadequate information to guide decisions on health policies and resource allocation is one of the obstacles for better policy development. Rational decisions on resource allocation based on health outcomes essentially require adequate tools. One of the tools developed by researchers at the Harvard University and the World Health Organization for the World Banks 1993 World Development Report is a comprehensive method of measuring loss of health in populations using the disability-adjusted life years (DALYs) that combines both the mortality and morbidity components of disease and injury". (6)

The Malaysian researchers have accurately identified two major functions of the DALY system, which are

1. The positive exercise of measuring the burden of disease, and

2. The normative exercise of resource allocation. (7)

WHO staff, which assumed management of the DALY measurement system from The World Bank around 2000, cautioned users of DALY data: The DALY is "a tool to assist cost-effectiveness analysis" and that the DALY measure "should not be used as the only tool for prioritization or resource allocation but should be assessed along with criteria such as issues of justice and equity, human rights, community preferences, etc.". (7)

II. The DALY Measure

The DALYs (Disability Adjusted Life Years) are time-based composite measures of the overall burden of disease due to

• Losses from premature death, and
• Non-fatal disability. (8)

WHO and HSPH staff in the early 1990s derived the DALY calculations for diseases and injuries and their sequelae according to 107 causes of death and 483 disabling sequelae in the International Classification of Diseases-Ninth Revision (ICD9). (9) The WHO publishes the ICD. The ICD, which is in its tenth revision (ICD10) assigns every health condition a unique category and code, up to six characters long.

A. Years of Life Lost

To determine the number of years of life lost due to premature mortality, researchers assigned to all deaths in 1990 a disease category and grouped by age, sex and demographic region. The researchers determined the disease (injury) category from death records where available and expert judgment where not. (8)

The researchers then estimated the number of health years of life lost (YLLs), based on the differences between the actual ages at death and an ideal standard life expectance at those ages. The standard life expectancy used for was 82.5 years at birth for women, and 80.0 for men for all countries irrespective of current life expectancy calculations. (8) Murray and Lopez selected the difference of 2.5 years between males and females to represent the potential true biological difference. (10)

B. Years Lived with Disability

For disability, researchers estimated the incidence of cases by age, sex and demographic region from community surveys or, where that was not available, expert opinion. (11) Researchers then obtained the number of years lived with disability (YLDs) by multiplying the expected duration of the disability (to remission or to death) by a disability weight that measured the severity of the disease compared with death. (11) The researchers defined seven disability classes. An expert-generated weighting between perfect health (0) and death (1) represented the severity of each disablement. (11)

The researchers assigned severity weights to each of the 483 disabling sequelae using a two-step process. First, they selected 22 conditions to encompass a wide range of disability severities and different health states. A group of twelve health professionals from around the world then assigned weights to these conditions by person-trade off methods described elsewhere. (11) WHO staff wrote in 1998:

"When making their assessments, individuals were asked to evaluate the average individual with the condition described taking into account the average social response or milieu. These weights were then arbitrarily divided along the spectrum form perfect health to death, into seven disability classes. Next, the remaining 461 conditions and sequelae were categorized into the same seven classes by expert opinion". (11)

C. Generating the DALY from its Components

The unweighted (see below) number of DALYs lost due to a specific disease or injury is

• Time lost due to premature death = expected life time age at death
• Time lived with disability = duration of the disability x severity weighting

Murray, Lopez and others took two more steps to produce the final set of DALY figures. First, a group of public health experts used "a modified Delphi method to ascertain a continuous age weight function; that is, the value of each year of life lost rises steeply from zero at birth to a peak at age 25 and then declines with increasing age. Thus, a year of young or middle-aged adult life is valued higher than that of young children or the elderly". (11)

Second, the researchers used a yearly discount rate of three percent to value future years of health life at progressively lower levels. WHO staff write,

"Using a rate of 3 percent means, for example, that one year of healthy life is counted as approximately half a year if it occurs 22.5 years from now, and only as 3 months if it occurs some 45 years into the future. The arguments for and against discounting are summarized elsewhere, however, three percent is noted as the lower limit of acceptability for those economists who are persuaded by opportunity cost arguments and is the upper limit for public health practitioners who are willing to accept a positive discount rate." (12)

III. Estimated Global Burden of Disease/Injury in DALYs Lost per 1,000 Population, 1990

Researchers calculated the number of DALYs lost per 1,000 population in eight demographic regions in the world for the year 1990 (see bar graph below). The Note that premature mortality is in vertical lines and disability is in diagonal lines within each bar. Sub-Saharan Africa lost almost 600 DALYs per 1,000 people in 1990 (given the current state of the art of data availability and collection), as compared with almost 200 DALYs per 1,000 people in the formerly socialist economies of Europe. (14)

Source: The World Development Report 1993. The World Bank, Oxford University Press, 1993, p. 3. Available at http://files.dcp2.org/pdf/WorldDevelopmentReport1993.pdf; accessed February 19, 2008.

IV. Disease Burden in DALYs Lost for 10 Leading Causes, 1998 and 2020

Source: A 5-Year WHO Strategy for Road Traffic Injury Prevention. World Health Organization, Geneva, 2001, p. 5.Available at http://www.who.int/world-health-day/previous/2004/en/final_strat_en.pdf; accessed February 24, 2008.

This list of the top ten causes for global disease burden provides a roadmap for where organizations may best attention. Note that there is an evidence-based expectation that road traffic injuries will move from #9 in the list in 1998 to #3 in 2020. (15)

V. Estimated Global Burden of Disease from Selected Environmental Threats, 1990

Environmental threats measured for 1990 included

• Occupational (cancers, neuropsychiatric, chronic respiratory, musculoskeletal and unintentional injury);
• Urban Air (respiratory infections, chronic respiratory)
• Road transport (motor vehicle injuries). (16)

Source: The World Development Report 1993. The World Bank, Oxford University Press, 1993, p. 95. Available at http://files.dcp2.org/pdf/WorldDevelopmentReport1993.pdf; accessed February 19, 2008.

VI. Road Traffic Injuries

Approximately 32 million road transport (motor vehicle injuries) DALYs occurred worldwide in 1990. Researchers calculated that of these 32 million DALYs for road traffic injuries, "feasible interventions" could avert 20 percent, or 6.4 million DALYs per year, which translates to 1.2 DALYs per 1,000 population per year.

As result of this data, WHO staff have noted with concern that "road traffic injuries constitute a major public health concern". They cause an estimated 1,171,000 deaths annually and many more cases of disability. They happen to people from all economic groups but more often to the poor". (17) They are the leading cause of death by injury, the 10^th leading cause of all deaths and the 9th leading contributor to the burden of disease worldwide. (18) "They constitute a rapidly growing problem with deaths from injuries projected to rise from 5.1 million in 1990 to 8.4 million in 2020. Rapid urbanization and motorization in developed countries will account for much of the rise and the rise will be steeper due to lack of appropriate road engineering and lack of injury prevention programs in the public health sector". (18)

Two reasons why road traffic DALYs are so high, and getting higher each year, in low-income and middle-income countries are uncertainty exists as to who is responsible for mitigating thempublic health agencies or transport agencies. (19) "Uncertainty as to who should be concerned means that no one takes responsibility for focusing on the problem and coordinating multi-agency and multi-disciplinary responses", note WHO staff. What is the best way to mitigate the injuriesfocus on behavioral changes such as wearing seat belts or focus on making the traffic environment safer? "Making the traffic environment safer may be a more important consideration in low-income countries, where many of the poor never drive vehicles but are still at considerable risk of being hit by them". (19)

The WHO admits that in 1974 it passed a resolution to address the growing problem of road traffic collisions and their health consequences, but over the years continued interest in the topic was sporadic and unsustained. "In 2000 the Injuries and Violence Prevention programme at the WHO was given full departmental status", which has placed the full weight of the WHOs constitutional mandate behind activities in road traffic injury prevention. (19)

VII. Summary

Road traffic injuries cause significant premature death and disability globally, as measured by DALYs in the global burden of disease measurement system initiated by The World Bank and now run by the World Health Organization in the early 1990s. The DALYs associated with road traffic injuries is rapidly increasing, so that by 2020, road traffic injuries will be the third highest in a list of the ten major causes of the global burden of disease. Improving prevention and mitigation of road traffic incidents in low-income and middle-income countries will help those countries better use their scarce resources (i.e., reduce the amount going to health care for people injured in road traffic incidents) and will improve safety for visitors.

Notes:

1. "Country Classification". The World Bank. Available at http://web.worldbank.org/WBSITE/EXTERNAL/DATASTATISTICS/0,,contentMDK:20420458~menuPK:64133156~pagePK:64133150~piPK:64133175~theSitePK:239419,00.html; accessed February 24, 2008. The World Banks website is at http://www.worldbank.org/; accessed February 19, 2008.
2. Lauren Giles, Elisabeth Hayes, and Mark Rosenberg: "Road traffic injuries: Can we stop a global epidemic?" The Doctor Will See You Now. Available at http://www.thedoctorwillseeyounow.com/articles/other/road_33/; accessed February 25, 2008.
3. "About the global burden of disease project". World Health Organization. Available at http://www.who.int/healthinfo/bodabout/en/index.html; accessed February 19, 2008. The World Development Report 1993. The World Bank, Oxford University Press, 1993, p. x. Available at http://files.dcp2.org/pdf/WorldDevelopmentReport1993.pdf; accessed February 19, 2008. The Global Burden of Injury report is in Appendix B, pp. 213-225.
4. A list of World Health Organization member states (193) is available at http://www.who.int/countries/en/; accessed February 24, 2008.
5. Alan D. Lopez: "The evolution of the Global Burden of Disease framework for disease, injury, and risk factor quantification: developing the evidence base for national, regional and global public health". Globalization and Health, 2005, Volume 1, pp. 1-12. Available at http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1143783; accessed February 15, 2008.
6. Ahmad Faudzi Yusoff: "Malaysian burden of disease and injury study". Division, Burden of Disease, Institute for Public Health, National Institute of Health, Malaysia, September 2005. Available at http://www.globalforumhealth.org/filesupld/forum9/CD%20Forum%209/papers/Yusoff%20F.pdf; accessed February 24, 2008.
7. DALYs and Reproductive Health", April 27-28, 1998. Division of Reproductive Health, World Health Organization, p. 1. Available at http://www.who.int/reproductive-health/publications/RHT_98_28/index.htm; accessed February 24, 2008.
8. Ibid, p. 2.
9. For more on ICD9 Codes, see http://en.wikipedia.org/wiki/List_of_ICD-9_codes and; http://en.wikipedia.org/wiki/ICD#ICD9; accessed February 24, 2008.
10. CL Murray and A Lopez: The Global Burden of Disease: A comprehensive assessment of mortality and disability from diseases, injuries and risk factors in 1990 and projected to 2020. Volume 1. Geneva, 1996.
11. DALYs and Reproductive Health", April 27-28, 1998. Division of Reproductive Health, World Health Organization, p. 3. Available at http://www.who.int/reproductive-health/publications/RHT_98_28/index.htm; accessed February 24, 2008.
12. Ibid, p. 6.
13. Robyn Norton, et al: Chapter 39: Nonintentional Injuries". Disease Control Priority Projects, p. 737. Available at http://files.dcp2.org/pdf/DCP/DCP39.pdf; accessed February 24, 2008.
14. The World Development Report 1993. The World Bank, Oxford University Press, 1993, p. 3. Available at http://files.dcp2.org/pdf/WorldDevelopmentReport1993.pdf; accessed February 19, 2008. The Global Burden of Injury report is in Appendix B, pp. 213-225.
15. A 5-Year WHO Strategy for Road Traffic Injury Prevention. World Health Organization, Geneva, 2001, p. 5.Available at http://www.who.int/world-health-day/previous/2004/en/final_strat_en.pdf; accessed February 24, 2008.
16. The World Development Report 1993. The World Bank, Oxford University Press, 1993, p. 95. Available at http://files.dcp2.org/pdf/WorldDevelopmentReport1993.pdf; accessed February 19, 2008.
17. A 5-Year WHO Strategy for Road Traffic Injury Prevention. World Health Organization, Geneva, 2001, foreword. Available at http://www.who.int/world-health-day/previous/2004/en/final_strat_en.pdf; accessed February 24, 2008.
18. Ibid, p. 1.
19. Ibid, p. 3.