Global Health in the 21st Century

Researchers at the World Health Organization, the Harvard School of Public Health, and collaborators from around the world have worked for several years to produce a 10-volume report entitled "The Global Burden of Disease and Injury Series." The reports are based on a set of estimates of the current patterns of mortality and disability from injuries and diseases in all regions of the world, and predictions for the patterns in the year 2020.

The work presents statistics on the leading causes of death in populations in the developed and developing regions of the world, but also factors in the impact of premature death and disability on the population, and combines all these into a measurement called the burden of disease. Authors of the Global Burden of Disease study present their findings as a resource for health planners and policy makers.

Some of the more striking findings in their report:

• By the year 2020, tobacco (a major risk factor for chronic obstructive pulmonary diseases like emphysema, and cancers of the lung, bronchus and trachea) is expected to kill more people than any single disease, surpassing even the HIV epidemic.
• Men living in the former USSR and socialist economies in Europe have a poor and deteriorating health status, including a 28% risk of dying between the ages of 15 and 60.
• The burdens of mental illnesses like depression, alcoholism, and schizophrenia have been seriously underestimated by traditional approaches to world health assessment which take into account death, but not disability. Psychiatric conditions are responsible for a little more than 1% of deaths, but they account for nearly 11% of the disease burden in the world.

The traditional killers in developing countries -- communicable diseases, maternal and perinatal conditions, and nutritional deficiencies -- still take a large toll despite improvements in the past several decades. But the projections indicate that even in developing countries, non-communicable diseases like depression and heart disease are beginning to replace malnutrition and infectious disease as the leading causes of premature death and disability.

Deaths from noncommunicable diseases are expected to increase by 77%. The projected increase is due to the aging of the population, where birth rate is falling and life expectancies are increasing. Another factor is the increase in the numbers of people who are exposed to tobacco in developing regions, which is referred to in the report as "the tobacco epidemic."

Injuries due to accidents and violence are also increasing their impact, and may rival infectious disease as a source of ill health by 2020.

The predicted change in the pattern of diseases and risk factors affecting global health is summarized in the table below, which lists the 15 leading categories of disease and disability in 1990 and the predicted top 15 for the year 2020. In 1990 the three leading causes of disease burden were pneumonia, diarrheal diseases, and perinatal conditions. By 2020 the three leading causes are expected to be ischemic heart disease, depression and traffic accidents. Measles will no longer be in the top 15, but tuberculosis is expected to continue to impose a serious burden of disease on the world population, and HIV (28th in 1990) is predicted to be the tenth leading cause of disease burden.

Rank Order of Disease Burden for 15 Leading Causes

Disease or Injury 1990	Rank	Disease or Injury 2020	Rank
Lower respiratory infections (pneumonia)	1	Ischaemic heart disease	1
Diarrhoeal diseases	2	Unipolar major depression	2
Perinatal (newborn) conditions	3	Road traffic accidents	3
Unipolar major depression	4	Cerebrovascular disease (stroke)	4
Ischaemic heart disease	5	Chronic obstructive pulmonary disease	5
Cerebrovascular disease	6	Lower respiratory infections	6
Tuberculosis	7	Tuberculosis	7
Measles	8	War	8
Road traffic accidents	9	Diarrhoeal diseases	9
Congenital anomalies	10	HIV	10
Chronic obstructive pulmonary disease	11	Perinatal conditions	11
Malaria	12	Violence	12
Falls	13	Congenital anomalies	13
Iron deficiency anemia	14	Self-inflicted injuries	14
Protein-energy malnutrition	15	Trachea, bronchus and lung cancer	15