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People around the world are living longer than they did two decades ago, but many people aren't very healthy during those extra years.
That's a key finding from a large-scale study estimating what makes people sick worldwide.
Researchers from over 300 institutions drew conclusions from nearly 100,000 data sources, including surveys, censuses, hospital records and verbal autopsies. They then used computer models to estimate how long people live and how healthy they are.
From 1990 to 2010, life expectancy continued to tick up in most parts of the world. The average age of death rose to 70 from 59, with women outliving men by about five years.
But the number of years that people live with chronic diseases and disabilities, like depression, back pain, arthritis and diabetes, has also increased.
The world's population is aging. And what makes us sick is no longer killing us as often or as early. But chronic illnesses are hurting quality of life.
"There may have been a perception that this is a problem in rich societies," says Joshua Salomon, a global health specialist at the Harvard School of Public Health. "It's a global problem, and it's predictive of what's coming – a tide of disability," he tells Shots.
Salomon, who worked on two of the seven papers in a package published by The Lancet, says the extra years come near the end of life, when many people have disabilities.
The rise in chronic illnesses is apparent in most parts of the world, except in sub-Saharan Africa, where infectious diseases, like diarrhea, AIDS and malaria are still major problems.
Elsewhere, Japan and Singapore are leading the way in healthy aging. Their people enjoy, on average, almost 70 years of disease-free living. Taiwan, Switzerland, Spain and Italy aren't far behind.
The U.S. ranked about 32nd in healthy life expectancy, behind both Canada and the U.K.
Here's some of the other big themes that emerge from the study:
Although the analysis offers a big-picture look at health around the world, some researchers caution that the details shouldn't be overinterpreted.
For some countries, the researchers had to use complex computer models and statistical tricks to estimate cause of death and life expectancy from relatively sparse data.
Estimates made with this approach are subject to large errors, says Charlotte Watts, an epidemiologist at the London School of Hygiene and Tropical Medicine, who worked on the study. "I'm pretty good at modeling, and I still don't know what's going on sometimes. It's such a complicated process."
This study was funded by the Bill & Melinda Gates Foundation, which also supports NPR.