12 June 2008

Global Causes of Death Move from Infectious to Chronic Diseases

Trend due to aging populations in middle-, low-income nations, WHO says

A doctor points out one of the three major coronary arteries on a model of the human heart.

By Cheryl Pellerin
Staff Writer

Washington -- Globally, causes of death will shift from infections like AIDS and malaria to chronic illnesses like heart disease and cancer, a new World Health Organization (WHO) report finds.

World Health Statistics 2008, published May 19, presents the most recent health statistics for WHO’s 193 member states on 73 health indicators. This fourth edition has 10 highlights in health statistics, including a section on “Future Trends in Global Mortality: Major Shifts in the Causes of Death Patterns.”

According to the report, the four leading causes of death in the world in 2030 will be ischemic heart disease (involving lack of blood flow and oxygen to the heart muscle), stroke, chronic obstructive pulmonary (lung) disease, and lower-respiratory infections (mainly pneumonia).

“The decline in infectious diseases is driven largely by [an] epidemiological transition,” Colin Mathers, coordinator for country health information at WHO in Geneva, told America.gov, in which disease trends change with economic development -- infectious diseases in less-developed nations and noncommunicable chronic diseases in developed nations whose populations have better nutrition, living conditions and health care.

“The rise of heart disease and cancers is driven by population aging,” said Mathers, lead investigator for the projections. “Populations will grow and get older, which is also a reflection of the lower death rates from infectious diseases.”

2030 PROJECTIONS

Globally, cancer deaths will increase from 7.4 million in 2004 to 11.8 million in 2030, and deaths from cardiovascular diseases will rise from 17.1 million to 23.4 million, the report predicted.

The report included road traffic accidents, saying deaths from this source will increase from 1.3 million in 2004 to 2.4 million in 2030, mainly due to increased motor vehicle ownership and use associated with economic growth in low- and middle-income countries.

By 2030, deaths from cancer, cardiovascular diseases and traffic accidents together will account for 56 percent of the projected 67 million deaths from all causes.

The increase in deaths from noncommunicable diseases will be accompanied by large declines in mortality from the main communicable, maternal, perinatal (five months before and one month after birth) and nutritional causes, including HIV infection, tuberculosis and malaria.

Residents of a housing complex for senior citizens in Pune, India

Deaths from HIV/AIDS are expected to rise worldwide from 2.2 million in 2008 to a maximum of 2.4 million in 2012 before declining to 1.2 million in 2030.

These shifting health trends indicate that leading infectious diseases -- diarrhea, HIV, tuberculosis, neonatal infections and malaria -- will become less important causes of death globally over the next 20 years.

PAST AND FUTURE

The starting point for the projections, Mathers said, is the WHO Global Burden of Disease project, which estimates deaths by cause for every region of the globe.

“For the actual projections of deaths,” he added, “we look at the available data from predominantly high- and middle-income countries from death registration data over the last 50 years and see how rates for major causes of death change as countries develop.”

The trends then are applied to developing countries, he added, on the assumption that what happens in the developing world with economic development will follow similar trajectories to what has happened in more developed countries over the past 50 years.

“The projections essentially assume the future will be like the past,” Mathers said, “and that’s always an uncertainty.”

Factors used to establish a nation’s level of development include gross national income per capita based on World Bank economic projections, average years of schooling for adults, projected improvements over time in health care technology, and smoking levels in the population.

“If we had the information,” Mather said, “we’d probably add other risk factors like overweight and obesity and so on. But we don’t have good data going back.” The projections also do not account for potentially substantial health effects of pandemics and other disasters.

Although the numbers of deaths will rise along with population growth, Mathers said the projections actually show small declines in the death rate at any given age.

“It’s reflecting an improvement in health,” he said. “We’re living longer and so more of the deaths are from the diseases that affect very old people. It’s the same with disabilities like arthritis or Alzheimer’s disease. People say the population is aging and we’ve got an epidemic of Alzheimer’s, but on the whole, people are getting more useful years of life, even if they do end up getting Alzheimer’s at an age when they would have been dead in a previous generation.”

The full World Health Statistics 2008 report is available at the WHO Web site.