But what about sickness? For all their relative benefits, mortality figures do not capture the huge toll of sickness and disability caused by diseases that stop this side of death, keeping workers off the job and children out of school and generally slowing both economic and social development. Yet statistics on disease incidence, or morbidity, are even harder to come by than are mortality numbers. In addition, the few figures that do exist tend to be biased because wealthier people seek medical care much more often than the poor.
Over the years various investigators have attempted to overcome these limitations by developing new metrics that factor in disability or quality of life along with mortality. One of the most recent – and still controversial – measures is the Disability-Adjusted Life Year, or DALY.
| The disproportionate disease Burden in Africa | |
| Disease burden by gender and demographic region | |
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| Source: Christopher J.L. Murray and Alan D. Lopez, eds., The Global Burden of Disease: Volume 1 (World Health Organization, Harvard School of Public Health, and the World Bank, Geneva, 1996), pp. 541-612. | |
DALYs combine losses from premature death (defined as the difference between the actual age of death and life expectancy at that age in a low-mortality population), and loss of healthy life resulting from disability. In simple terms, a DALY strives to tally the complete burden that a particular disease exacts. Key elements to consider include the age at which disease or disability occurs, how long its effects linger, and its impact on quality of life. Losing one’s sight at age 7, for instance, is a greater loss than losing one’s sight at 67. Similarly, a bout of acute illness that is over quickly counts less in the DALY calculation than one that leaves lingering weakness, such as persistent worm infections.
This new indicator can be used in different ways to compute the total burden of a particular disease, such as malaria (which accounts for some 65,578,000 DALYs per year), or to tally up the total global burden of disease (in 1990 the world’s population lost 2,480,237,000 DALYs), or to compare the relative burden of disease among different regions of the world [44].
Looked at from this perspective – which considers not just premature death but disability as well – the huge toll of ill health in developing countries stands out even more starkly. Nearly nine tenths of the global burden of disease occurs in developing regions where only 1 in 10 health care dollars are spent [45]. As the Disproportionate Disease Burden in Africa
shows, sub-Saharan Africa suffers twice the burden of ill health as the global average and nearly five times more than the richest countries.Using this new metric, communicable diseases are the single most important cause of ill health globally, accounting for 44 percent of the total. (Deaths versus DALYs compares the 10 leading causes of death with the 10 leading causes of DALYs.) This increase in the relative importance of infectious diseases reflects in large part the early age at which they strike. Of the top 10 causes of DALYs globally, communicable diseases account for 7, with lower respiratory infections and diarrheal diseases heading the list [46]. DALYs also underscore the disproportionate burden of ill health borne by the world’s children. Children under age 15 account for almost one half of all lost DALYs worldwide. As the following discussion makes clear, the diseases that most affect children tend to be heavily influenced by environmental factors.
References and notes
44. Christopher J. L. Murray and Alan D. Lopez, eds., The Global Burden of Disease: Volume 1 (World Health Organization, Harvard School of Public Health, and The World Bank, Geneva, 1996), p. 609.
45. Christopher J. L. Murray and Alan D. Lopez, eds., The Global Burden of Disease: Volume 1 (World Health Organization, Harvard School of Public Health, and The World Bank, Geneva, 1996), p. 254.
46. Christopher J. L. Murray and Alan D. Lopez, eds., The Global Burden of Disease: Volume 1 (World Health Organization, Harvard School of Public Health, and The World Bank, Geneva, 1996), p. 175.
