A novel study that attempts to paint the most accurate and detailed description yet of how we experience pain has found that a significant portion of the population -- 28 percent -- are in pain at any given moment and those with less education and lower income spend more of their time in pain. Those in pain are less likely to work or socialize with others and are more inclined to watch television than the pain-free.

The study, which appears in the May 3 issue of The Lancet, was prepared by Alan Krueger, a professor of economics at Princeton University, and Arthur Stone, a professor of psychiatry and behavioral science at Stony Brook University. The work is the first of its type, according to the authors, to quantify a "pain gap" in American society, with the "have-nots" suffering a disproportionate amount in relation to the "haves."

"To a significant extent, pain does divide the classes," said Krueger, the Bendheim Professor in Economics and Public Policy. "And just how the levels of pain vary among people and across activities -- that has never been found before until now."

Participants with less than a high school degree were found to report twice the average pain rating throughout the day as did college graduates. The researchers also found the average pain rating to be twice as high for those in households with annual incomes below $30,000 as for those in households with incomes above $100,000.

"People in households making less than $30,000 a year spend almost 20 percent of their time in moderate to severe pain, compared with less than 8 percent for those in households with income above $100,000 a year," Krueger said.

Pain imposes considerable costs on the health care system and economy. Americans spend billions of dollars each year on painkillers, more than on any other type of medication. And, when workers are suffering, the resulting lost productivity costs business more than $60 billion annually.

Yet, according to Krueger, the phenomenon of pain -- who is in pain and when -- is not well understood.

The authors constructed a new approach in which participants, a representative group of 4,000 Americans, reported their activities and the occurrence and intensity of pain in a diary survey over a 24-hour period. From the data, the researchers could tie the participants' pain to certain activities, demographic characteristics and times of the day. Pain tended to be more frequent when people received medical care or cared for adults.

The researchers did not ask the survey participants to make a distinction between physical and mental pain because all pain, the researchers said, is subjective. Yet clearly, they said, many of the participants were reporting physical pain.

"The novelty of this study is the possibility to relate people's pain experiences to their daily activities," wrote Juha H.O. Turunen, a professor in the Department of Social Pharmacy at the University of Kuopio in Finland, in an accompanying commentary.

The study, Turunen noted, may have broad implications for policymakers. Social programs could be constructed to help those who are in pain while caring for relatives. "The burdensome life of those caring for their loved ones must be supported by society," he wrote. The differing levels of pain recorded by varying income groups, he said, "emphasizes the need for pain preventing measures such as better ergonomics and better availability of occupational health services for jobs with high physical strains."

Workers in blue collar jobs reported higher occurrences and more severe pain than did those in white collar jobs. For blue collar workers, pain was lower when they were off work than when they were working. The 13 percent of people who reported a work-related disability experienced very high rates of pain, and accounted for 44 percent of the total amount of time that Americans spent in moderate to severe pain.

Those in the most pain expressed the least satisfaction with life and health, the authors found. People were more likely to feel pain when they were alone compared with when they were with friends or a spouse. In addition, those in pain spent a disproportionate amount of their time -- almost 25 percent -- watching television, compared with 16 percent for others.

Alarmingly, those in pain were likely to suffer over years, even decades. "The pain doesn't go away in many cases, when people stop working," Krueger said. Pain was higher and more common for older individuals, but the amount of pain reported remained relatively constant for individuals from their mid-40s to their mid-70s.

The survey, called the Princeton Affect and Time Survey, was designed by the authors and administered by the Gallup Organization in a telephone survey from May through August 2006. The research was funded by the National Institute on Aging and the Hewlett Foundation. The study and underlying data are available on Krueger's website.

The survey is an outgrowth of work Krueger and Stone conducted with Nobel laureate Daniel Kahneman, Princeton's Eugene Higgins Professor of Psychology Emeritus and senior scholar in the Woodrow Wilson School of Public and International Affairs, on measuring well-being and time use.

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