RAND Study Says Disability Rates Rise, Finds Link to Obesity

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January 8, 2004

The obesity epidemic caused disability rates to rise sharply in the last two decades among Americans younger than 60, according to a new study by RAND Corporation researchers.

The RAND Health study was published in the January edition of the journal Health Affairs.

The study found that the number of people ages 30-49 who were disabled in their ability to care for themselves or perform other routine tasks increased by more than 50 percent from 1984 to 2000.

For people ages 30-39, the number reporting disabilities rose from 118 per 10,000 people to 182 per 10,000 people from 1984 to 1996. For those ages 40-49, the numbers rose from 212 per 10,000 to 278 per 10,000 during the same period. In addition, researchers found smaller but still significant increases for those ages 18-29 and those ages 50-59.

In contrast, disability declined by more than 10 percent for people ages 60-69, the study found.

The study results surprised researchers, who warn that the increase in the disability rate could have severe consequences for the nation’s future health costs.

“People who are disabled generally use a lot more medical services so in the long run this trend could add a lot of costs to the nation’s health care bill,” said Dana Goldman, a study co-author and director of health economics at RAND Health.

Some portion of the rise in disability may be explained by disability insurance incentives and advancing medical technology that saves the lives of people who even a few years ago might have died, according to the study. But the only factor researchers could identify that would explain such a large jump in disability is obesity.

“Obesity is the only trend that is commensurate in size with what we found happening with disability,” said Darius Lakdawalla, lead author of the report and a RAND economist. “It’s the only suspect. We found that there is something going on with people’s health and that the increase is not just a case of people dropping out of the workforce and going on the public dole.”

Musculoskeletal problems (such as chronic back pain), which are linked to obesity, are one of the nation’s leading causes of disability, along with mental illness. Obesity also is a major factor in the development of diabetes, which accounts for a small number of disability claims.

The number of disability cases attributed to musculoskeletal problems (primarily back problems) and diabetes grew more rapidly than those from other problems during the study period, with the proportion of diabetes-related disability doubling.

Since 1984, disability among the nation’s older population has dropped, even though this group was considered most at risk for disabilities, the RAND study found.

Researchers had known that the number of people filing for disability benefits had risen during the study period. But the increase generally had been attributed to relaxed standards for disability claims that have made it easier to file for benefits.

Researchers found that disability rates rose for all demographic groups not in the age 60-69 category: for whites and non-whites, for those who worked and those who didn’t, and for people with all levels of education.

Researchers conducted the study by examining information collected from 1984 to 2000 by the National Health Interview Survey, a nationwide survey that collects a wide array of information from about 36,000 households annually.

Beginning in 1984, the survey asked participants a variety of questions about whether they needed help with personal care or other routine needs—the information analyzed by RAND Health researchers.

RAND researchers say their findings show there should be better efforts to study disability trends among younger people.

“We need to study this trend further and improve our measurement tools because the rise in disability has enormous consequences for public finances,” Goldman said.

Support for the study was provided by the Centers for Medicare and Medicaid Services and the National Institute on Aging. Jay Bhattacharya, an assistant professor of medicine at the Stanford University School of Medicine, is another author of the report.

RAND Health is the nation’s largest independent health policy research organization, with a broad research portfolio that focuses on health care quality, costs, and delivery, among other topics.