THURSDAY, Oct. 7 (HealthDay News) -- A new study finds that 22 percent of adults in the United States -- 49.9 million people -- have been diagnosed with arthritis and that 42.4 percent of those people experience arthritis-related limitations in activity.

The analysis of data from the 2007-2009 National Health Interview Survey also shows that the prevalence of arthritis and associated activity limitations is on the rise, likely because of the aging population and high rates of obesity, the researchers said.

They noted that one in three obese adults reports having arthritis.

One leading advocacy group agreed that the new numbers are sobering.

"The report confirms arthritis is common, costly and disabling," Arthritis Foundation president and CEO Dr. John H. Klippel said in a statement. "The number of adults with arthritis has increased by nearly one million per year and it is impacting the usual activities of an unprecedented 21 million adults."

He added that, "with some 67 million Americans projected to have arthritis by 2030, now is the time to escalate efforts to prevent, treat and cure the most common cause of disability in the United States."

The researchers note that the prevalence of arthritis could be reduced, at least in part, by greater promotion of effective physical activity, obesity prevention and self-management education programs in local communities.

The study appears in the Oct. 8 issue of Morbidity and Mortality Weekly Report, published by the U.S. Centers for Disease Control and Prevention.

More information

The U.S. National Institute on Aging has more about arthritis.