Number of ailments in older adults after retirement is directly linked to shortened life expectancy, a new research by the Johns Hopkins Bloomberg School of Public Health shows.

The study was based on the analysis of 1.4 million Medicare enrollees, a nationally representative sample of Medicare beneficiaries, registered as of January 1, 2008. The data included 21 defined chronic conditions and the participants were aged 67 or above.

Researchers found that on average life expectancy reduced by 1.8 years with each additional chronic condition.

The United States have nearly four in five elderly people living with multiple chronic medical conditions.

"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," lead study author Eva H. DuGoff, said in a press release.

"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."

The researchers found that on average, a 75-year-old American woman with no chronic conditions will live 17.3 additional years. However, a same aged woman with five chronic conditions will have reduced life expectancy and will live till 87 on average.  And a 75-year-old woman with 10 or more chronic conditions will only live to the age of 80.

Researchers noted that women continue to live longer than men and white people live longer than black people.

The team further said that at 67, a heart disease patient has chances to live an additional 21.2 years on average. But, those diagnosed with Alzheimer's disease might only live 12 additional years.

"We tend to think about diseases in isolation. You have diabetes or you have heart failure. But many people have both, and then some," explained senior author Gerard F Anderson, PhD, a professor in the Department of Health Policy and Management at the JHSPH. "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."

According to the researchers, the study results might be helpful to Social Security and Medicare planners as they make population and cost predictions for the future

"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 said. "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 study will appear in the August issue of the journal Medical Care.