Conclusions
Priority setting in health, as in other sectors concerned with social development, will increasingly depend on the availability of reliable, timely, representative, and relevant information on the comparative importance of diseases, injuries, and risk factors for the health of populations and how these are changing. Population scientists, particularly epidemiologists, have provided important insights into the descriptive epidemiology of some segments of some populations and on the causes of disease and injuries in those populations. Administrative requirements have resulted in most countries undertaking routine data collection efforts, but these are highly variable in terms of both quality and of what is being measured. As a result, we have substantial partial data collections on many aspects of population health status, but no country has complete data on all aspects of health relevant for policy, and in many parts of the world, health status is largely unknown. Efforts to bring these fragmentary pieces of data together to develop comprehensive estimates of the disease and injury burden and its causes are likely to be extremely valuable for policy making, particularly if the analytical methods and frameworks employed are understandable, transparent, and rigorously argued. Demographers were the first to attempt global, regional, and national efforts to estimate population size, structure, and determinants of change in a coherent fashion, and despite scientific differences of opinion about some of the methods and assumptions, the results have been enormously influential for guiding social development policies and programs.
The two GBD studies for 1990 (Murray and Lopez 1996) and 2001 (chapter 3 in this volume) attempted something similar for mortality and the burden of disease. Scholars and global health development agencies alike have repeatedly emphasized the interrelationship between demographic change and the health conditions of populations. This chapter has summarized the key quantitative findings about global demography and epidemiology that are relevant for disease control and public health development, leading to the following three broad conclusions:
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Despite significant investments in disease control in low-and middle-income countries over the past 50 years and the considerable success in reducing mortality, commensurate investments have not been made in the health intelligence base needed to monitor and evaluate changes in population health. As a result, uncertainty about the causes of child mortality in many countries and how these have changed over the last decade or so because of intervention programs is considerable. Moreover, data collection pertaining to health conditions among adults has been almost totally neglected, with the result that virtually nothing is known reliably about levels, let alone causes, of adult death in much of the developing world. HIV/AIDS has highlighted this neglect, but continued ignorance of the leading causes of adult mortality will continue to hinder policy action to reduce the large, avoidable causes of adult mortality that can be addressed through targeted prevention and treatment programs.
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Demographic change is often poorly understood, and thus potentially underappreciated in relation to health and social development policies. The evidence summarized in this chapter suggests that population aging is likely to become rapidly more pronounced in low- and middle-income countries than is currently appreciated, in part because swift fertility declines are under way in much of the developing world. The little evidence that is available about mortality trends among adults in developing countries suggests different paths of mortality change among regions, but indicates that globally, little progress was achieved in the 1990s. At older ages, the impressive and widely unappreciated declines in mortality that began in the high-income countries in the 1970s continued through the 1990s and show little sign of deceleration. In large part, these declines reflect progress in the control of major vascular diseases and point to continued steady gains in life expectancy in high-income countries.
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Despite at least two decades of intensive efforts by the global public health community to implement intervention programs and reorganize health services to reduce child mortality, knowledge about the major causes of death among children is insufficiently precise to resolve uncertainties about global progress with specific disease control strategies, and thus to be of maximum benefit for global policy action to reduce the more than 10 million child deaths that still occur each year. Results from the two GBD studies, while suggesting trends that are broadly consistent with public health knowledge, are equivocal about trends in specific conditions in some regions. Policy action to rapidly and substantially reduce this enormous burden of premature mortality will be better served if policy makers can be more appropriately informed about the causes of child death, including hitherto neglected areas such as perinatal conditions and injuries.
