Worldwide Study Finds Big Shift in Causes of Death
The first comprehensive, worldwide study of how people die has produced a number of startling findings, including the prediction that within 25 years smoking will become the single largest cause of death and disability in the world.
A five-year study by an international team headquartered at the Harvard University School of Public Health also found that noncommunicable diseases such as cancer, heart disease and diabetes already cause more deaths in the developing world than infectious diseases. This contradicts the prevailing belief that the noncommunicable diseases primarily strike the affluent.
The study, to be released today, found that depression, also thought to be largely associated with affluence, accounts for a full 10% of productive years lost throughout the world.
One of the bleakest outlooks is for residents of the former Soviet empire. Largely as a result of smoking, alcoholism and accidents, men in that region face a 28% risk of death between the ages of 15 and 60, the highest risk anywhere outside sub-Saharan Africa.
Because of this rapidly changing nature of death, the report argues, international health agencies should curtail their funding of routine vaccination programs and health care delivery and focus instead on research and development to minimize the impact of noncommunicable diseases.
The report is a “historic achievement,” said Dr. Barry R. Bloom of the Albert Einstein College of Medicine in New York City. “It shows that health risks will increasingly be shared across countries, that the health differences between countries will be narrowed.”
It provides “a global health agenda” that suggests to health agencies how money can best be spent “to get the most healthy life,” added Bloom, who is co-chairman of the Board on International Health of the National Academy of Sciences.
The study, called “The Global Burden of Disease,” is “an encyclopedic work and an heroic undertaking,” added John C. Caldwell, president of the International Union for the Scientific Study of Population. “There are pictures emerging from this book that most of us previously did not even dare to guess about.”
The report was necessary because many regions collect no death data at all and lack even the most basic data needed to direct health programs and guide research, according to Dr. Christopher J. L. Murray of Harvard, co-chairman of the committee that prepared the study, which was supported by the World Health Organization.
Most death rates for infectious diseases and other causes in developing countries, he said, are produced by groups trying to raise money to combat that disease and who often exaggerate its importance. If the previously available estimates of disease were all correct, he noted, some people in a given age group or region would have to die at least twice to account for all the deaths claimed.
At the opposite extreme, Murray said, “If there are no advocates for a condition, it never shows up at all.”
The team collected all the available government statistics for deaths and disabling conditions. Perhaps more important, in areas where data was not good, the researchers sampled a total of more than 14 million death certificates from which they could project numbers for the country or region as a whole.
The researchers also tabulated years of productive life lost to disability. They were then able to combine the number of years lost to disability with those lost to premature death to get a clearer idea of what they termed “disease burden.”
The first two volumes of results (of a projected 10 volumes) total 1,880 pages packed with insights into the ways people die.
Just over 50 million people died in 1990, the base year for the report. Worldwide, one of every three died from either communicable diseases, childbirth or malnutrition. Virtually all of those deaths were in developing regions. One of 10 deaths resulted from injuries caused by accidents, wars, suicides and homicides. About 55.8% of all deaths were from noncommunicable diseases, a proportion that is expected to jump to 73% by 2020.
By that same year, the report says, car accidents will be the world’s fifth-leading cause of death and disability as developing nations build more roads and the number of young adults--those most often killed in traffic mishaps--increases.
Surprisingly, Murray said, the team found that noncommunicable diseases were already responsible for more deaths than infectious diseases in all areas of the world except India and sub-Saharan Africa. Many researchers now mistakenly believe that once people in such developing regions get to adulthood, they have a greater chance of surviving than residents of developed countries because they have a low-fat, high-fiber diet, they smoke less and get more exercise, he said. “That’s not the case, and we need to find out why.”
More people die of heart disease than any other cause. And of the 6.3 million who died of it in 1990, only 2.7 million were in developed countries. Strokes killed 1.4 million people in developed countries and a total of 4.4 million worldwide. Worldwide, pneumonia killed 4.3 million people and diarrheal disease 2.9 million, nearly all of them in the developing countries.
The researchers calculated that smoking, because of its impact on heart disease, lung cancer and other disorders, caused 3 million deaths in 1990. That total will nearly triple to 8.4 million deaths in 2020, the report predicted, making it the single largest cause of death.
The primary reason for the increasing importance of noncommunicable diseases is the graying of the world’s population, the study concludes. As birthrates decline due to improved contraception and more children survive through childhood, the total population is getting markedly older. The proportion of the world’s people 45 or older will double by 2020, Murray said.
The report also found that a number of diseases, although they may not necessarily kill large numbers of people, have a significant impact on world health and productivity. Pneumonia, diarrheal disease and complications of birth are the leading contributors to years lost to disability and premature death. Depression is close behind, and by 2020, the report projects, will have moved up to No. 2, accounting for 15% of total disease burden, and trailing only heart disease.
“That’s very surprising,” Bloom said. “I wouldn’t have predicted that.”
The report’s conclusions strongly suggest that “the allocation of funds for research and development is often irrational and based on inadequate information,” said Dr. Tore Godal, director of the United Nations’ Special Programme for Research and Training in Tropical Diseases. “Some of the gravest health problems receive only pitiful resources, while comparatively small problems receive large shares.”
Research and development for tuberculosis, pneumonia and diarrheal diseases combined, he noted, amount to a minuscule 0.2% of total health research and development funding worldwide, yet those conditions account for nearly 20% of the global disease burden.
“Perhaps we are biting the hand that feeds our committee,” added Dean Jamison, a UCLA economics professor Dean Jamison and World Bank consultant who was on the panel that wrote the report. But he charged that international funding agencies have not been placing funds where they can do the most good. “They’ve too often used resources for routine operations such as vaccination programs, and have not been generating new tools that will affect broad regions. . . . We have to put our brains where our hearts have been.”
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
Disease Projections
The causes of death and disability are expected to change dramatically by the year 2020.
1990 rank: Disease or injury
1. Lower respiratory infections
2. Diarrheal diseases
3. Conditions arising during the perinatal period
4. Unipolar major depression
5. Ischemic heart disease
6. Cerebrovascular disease
7. Tuberculosis
8. Measles
9. Road traffic accidents
10. Congenital anomalies
****
2020 rank: Disease or injury
1. Ischemic heart disease
2. Unipolar major depression
3. Road traffic accidents
4. Cerebrovascular disease
5. Chronic obstructive pulmonary disease
6. Lower respiratory infections
7. Tuberculosis
8. War
9. Diarrheal diseases
10. HIV
Source: “The Gloval Burden of Disease,” by the World Health Organization, 1996.
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
A Global Killer
By 2020, smoking is projected to be the single largest cause of diseases that kill.
Region: % of deaths from tobacco
Established Market Economies: 14.9%
Former Socialist Economies: 22.7%
India: 13.3%
China: 16.0%
Other Asian Countries and Islands: 8.8%
Sub-Saharan Africa: 2.9%
Latin America/Caribbean: 9.4%
Middle Eastern Crescent: 12.3%
Worldwide: 12.3%
Source: “The Gloval Burden of Disease,” by the World Health Organization, 1996.
