In its Morbidity and Mortality Weekly Report for Oct. 8, the CDC estimates that nearly 50 million Americans have arthritis, and the joint disease is especially common among people who are obese.

The statistic comes from national telephone polling of tens of thousands of adults in 2007 through 2009.

The report also suggests there were about 42 percent adults with arthritis who said their joint pain or other arthritis symptoms limited their usual activities.

That means more than 21 million adults have trouble climbing stairs, dressing, gardening or doing other things, the CDC said.

The percentage of people who were hobbled was more than twice as high in obese people as those who were normal weight or underweight, the researchers found.

Obesity particularly plays a role in the onset of knee osteoarthritis, the most common form of the disorder.

The total cost of medical and impaired activity to the U.S. economy is about 128 billion U.S. dollars annually, the agency added. 

On Xinhua Web site: http://news.xinhuanet.com/english2010/health/2010-10/08/c_13546720.htm