Synthesizing data from multiple government-sponsored health surveys conducted over the last 21 years, Allison Rosen, MD, associate professor of Quantitative Health Sciences at UMMS, Susan Stewart, researcher at the National Bureau of Economic Research, and David Cutler, professor of economics at Harvard University, were able, for the first time, to measure how the quality-adjusted life expectancy (QALE) of all Americans has changed over time. The study's findings are described in a paper published today in the American Journal of Public Health.

"QALE tells us more than how long a person can expect to live," said Dr. Rosen, senior author on the study. "It tells us what the relative quality of those added years are in terms of physical, emotional and mental well-being. Though many studies have measured this in different ways, this is really the first time we've been able to capture this type of information across the whole U.S. population over an extended period."

The data shows that Americans are living longer, reporting fewer symptoms of disease, have more energy and show fewer impairment in everyday tasks such as walking than a generation ago. According to the study authors, a 25-year-old person today can expect to live 6 percent or 2.4 quality years longer than their 1987 counterpart. Meanwhile, a 65-year-old person will gain 1.7 quality years, a 14 percent increase from a generation ago.

Thanks to improvements in health care, many conditions are far more treatable today than 25 years ago, Rosen said. Heart disease, for instance, was potentially much more debilitating a generation ago and patients often suffered a decline in quality of life as a result. "Today, it is far less likely that a patient recovering from a heart attack will become institutionalized or need around-the-clock care the way they once might have," Rosen said. They also found that health gains made as a result of smoking cessation programs were being off-set, in part, by increases in obesity.

Today, Americans are more likely to see quality of life declines related to chronic, degenerative diseases such as Alzheimer's and dementia, while younger Americans appear to be experiencing problems related to a sedentary lifestyle.

The authors also identified some troubling health trends. Among these was an increase in anxiety among young and middle-aged people beginning in 2001. Problems with walking have increased significantly among non-elderly over the last decade.

In the past, researchers have had a difficult time measuring population health beyond simple life expectancy because quality of life incorporates so many variables -- physical well-being, mental health, pain, vitality, energy, emotional state -- that it's difficult to bring all these things together cohesively into a single number. Making it even more challenging, the surveys that measure quality of life are rarely consistent with each other because they all define health and quality of life differently.

Using multiple national surveys that asked Americans about their health in various ways over the last 21 years, the authors solved this problem by identifying areas where the studies overlapped, allowing them to build a single, large data set which covered the entire adult population over more than two decades.

"Comprehensive measures of the overall health of the nation are practically nonexistent," said Rosen. "This study shows how existing national data can be used to systematically measure whether the population is getting healthier -- not just living longer."

As the Affordable Care Act goes into effect in 2014, the value of a single, consistent way of measuring improvements in health over a large population will be invaluable in assessing the impact of these pending changes according to the authors.

"Having a consistent measure of population health represents a major advance in our ability to measure the impact of health care reform on the health -- not just the health care use -- of all Americans," said Rosen. "The bottom line in assessing the success of the ACA is whether or not we are getting the most health from our investment of increasingly limited resources. Are we getting the most health bang for our bucks?"