Chronic disease overlap cuts life expectancy

"We already knew that living with multiple chronic conditions affects an individual’s quality of life; now we know the impact on quantity of life," Eva DuGoff says. "The growing burden of chronic disease could erase decades of progress." (Credit: Papieren Geluk/Flickr)

Struggling with multiple chronic illnesses shortens life expectancy dramatically, and for older Americans, it threatens to reverse recent gains in average lifespans.

Nearly four in five older Americans now live with multiple chronic medical conditions, which perhaps could explain why increases in life expectancy for US seniors are already slowing, report researchers.


“Living with multiple chronic diseases such as diabetes, kidney disease, and heart failure is now the norm and not the exception in the United States,” says lead author Eva H. DuGoff, a graduate of the Johns Hopkins University’s Bloomberg School of Public Health.

“The medical advances that have allowed sick people to live longer may not be able to keep up with the growing burden of chronic disease. It is becoming very clear that preventing the development of additional chronic conditions in the elderly could be the only way to continue to improve life expectancy.”

Life expectancy in the US is rising more slowly than in other parts of the developed world. Many blame the obesity epidemic and related health conditions for the worsening health of the American population.

Current expectations

The researchers used a nationally representative sample of Medicare beneficiaries enrolled as of January 2008. The data included 21 defined chronic conditions and the records of nearly 1.4 million people 67 and older.

The analysis found that, on average, a 75-year-old American woman with no chronic conditions will live 17.3 additional years to more than 92 years old. But a 75-year-old woman with five chronic conditions will live, on average, only to age 87, and the average 75-year-old woman with 10 or more chronic conditions will survive only to age 80.

Women continue to live longer than men, while white people live longer than black people.

Which diseases, as well as how many, matters. At 67, an individual with heart disease is estimated to live an additional 21.2 years on average, while someone diagnosed with Alzheimer’s disease is only expected to live 12 additional years.

‘Greater than the sum of its parts’

On average, life expectancy is reduced by 1.8 years for each additional chronic condition, the researchers found. But in reality, the arithmetic is not that neat and simple: The first disease shaves off just a fraction of a year off life expectancy for older people, but the impact grows as the number of diseases adds up.

“We tend to think about diseases in isolation. You have diabetes or you have heart failure. But many people have both, and then some,” says senior author Gerard F. Anderson, professor of health policy and management at Johns Hopkins.

“The balancing act needed to care for all of those conditions is complicated; more organ systems become involved, as do more physicians prescribing more medications. Our system is not set up to care for people with so many different illnesses. Each one adds up and makes the burden of disease greater than the sum of its parts.”

The study’s findings, published in Medical Care, could be useful to Social Security and Medicare planners in making population and cost predictions.

Policymakers are facing a different landscape as so many more people are living with multiple chronic conditions than before: 60 percent of those 67 and older in the United States have three or more of these diseases, the researchers found. Eventually, there may be a tipping point, when the medical advances that have boosted life expectancy for so long can no longer keep pace with the many illnesses people are collecting as they age.

“We already knew that living with multiple chronic conditions affects an individual’s quality of life; now we know the impact on quantity of life,” DuGoff says. “The growing burden of chronic disease could erase decades of progress. We don’t want to turn around and see that life expectancy gains have stopped or reversed.”

The American Insurance Group supported the study.

Source: Johns Hopkins University