People live more than a decade longer on average today than they did in 1970, but spend much of these boon years battling diseases like cancer, according to a global health review published Thursday.
By 2010, a man's life expectancy at birth had risen 11.1 years from 1970 and that of a woman 12.1 years, said the bundle of seven studies published by The Lancet medical journal.
But as we live longer, bigger chunks of our lives are marred by illness, with non-infectious maladies like cancer and heart disease claiming ever more victims.
"Over the last 20 years, globally, we've added about five years to life expectancy, but only about four years to healthy life expectancy," Josh Salomon from the Harvard School of Public Health, a study partner, told AFP by email.
"You can think about it as adding the equivalent of four years of good health and one year of bad health."
Contributors to the study appealed for a shift in health policy focus from simply keeping people alive to keeping them healthy as well.
"Health is about more than avoiding death," said Alan Lopez and Theo Vos of the University of Queensland's School of Population Health in a joint statement.
The magnum opus is the work of nearly 500 authors from 50 countries, consolidating data from academic research papers, autopsy reports, hospital records and censuses, covering 291 types of disease and injury in 187 countries.
With the exception of sub-Saharan Africa, it shows a clear shift in the disease burden from traditional culprits like malnutrition, infectious diseases and birth complications that generally mow down younger people, to cancer, heart disease and diabetes that can linger for years.
The growing burden of disability "implies additional health care needs and costs in terms of both social costs, financial costs and the demands on health care delivery system," Salomon said.
The study said non-communicable diseases like cancer, diabetes and heart disease accounted for nearly two out of every three deaths in 2010 -- up from half in 1990.
Thirty-eight percent more people died of cancer in 2010 than in 1990 -- eight million compared to 5.8 million.
The number of deaths from malnutrition and infectious, maternal and neonatal diseases declined from 15.9 million in 1990 to 13.2 million in 2010.
"The big issue here is the transformation from risks really related to poverty at the global level to risks that are more profoundly related to a series of non-communicable diseases and the way people live their lives," study leader Christopher Murray of the University of Washington's Institute for Health Metrics and Evaluation told a recorded press conference.
In 2010, high blood pressure (9.4 million deaths) and tobacco smoking (6.3 million deaths) posed the biggest risks to health worldwide, followed by alcohol (five million deaths), the study said.
An unhealthy diet and physical inactivity were collectively responsible for an estimated 12.5 million deaths.
The study noted a sharp rise in chronic disability from causes like mental disorders, substance abuse, diabetes and muscular-skeletal ailments.
"These diseases that cause chronic disability, they tend to be related to age, so as populations get older and premature mortality rates go down, you have more people living into the age groups where these are quite common," said Murray.
"This is one of the broader transformations we see globally, particularly outside of sub-Saharan Africa."
In that part of the world, life expectancy of men decreased by 1.3 years over the four decades from 1970 and that of women by 0.9 years -- mainly due to HIV/AIDS.
In Botswana, South Africa, Zambia and Zimbabwe, deaths in the 15-49 age group rose by more than 500 percent from 1970.
"Belarus and Ukraine in eastern Europe also underwent notable declines in life expectancy, thought to be due to high rates of alcohol-related deaths in these countries," a statement said.
Globally, though, the study showed deaths in children younger than five dropping by almost 60 percent from 16.4 million deaths in 1970 to 6.8 million in 2010.
Japanese women had the world's highest life expectancy at 85.9 years, followed by Icelandic men at 80 years.
The impoverished island of Haiti had the lowest life expectancy (32.5 years for men and 43.6 for women), mainly due to the devastating 2010 earthquake that killed at least 250,000 people.
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