More than 22 percent of Americans have arthritis, with a million new cases being diagnosed every year, according to a new government estimate released on Thursday.

As the population ages, the problem will get worse and more expensive, too, the U.S. Centers for Disease Control and Prevention report said.

The CDC team used a large federal survey called the National Health Interview Survey, in which thousands of Americans are asked a battery of questions about their health.

Survey data from 2007 to 2009 showed 22 percent of Americans, or just under 50 million people, had arthritis diagnosed by a doctor, the CDC said in its weekly report on death and disease.

“After adjustment for age, arthritis prevalence was significantly higher among women (24.3 percent) than among men (18.2 percent),” the report reads.

Nearly 30 percent of the obese had arthritis, and those who exercised less, smoked more and who had lower levels of education were also more likely to have arthritis.

“Arthritis is a large and growing public health problem in the United States, resulting in costs of $128 billion annually, and continues to be the most common cause of disability,” the report reads.

“With the aging population and continued high prevalence of obesity in the United States, the prevalence of arthritis is expected to increase significantly over the next 2 decades,” the CDC added in a commentary on the report.

More than two-thirds of Americans are overweight or obese.

“Compared with previous estimates, the number of adults with arthritis increased, but not significantly, from 46.4 million during 2003-2005 to 49.9 million during 2007-2009, an increase of approximately 1 million adults per year.”

SOURCE:  Morbidity and Mortality Weekly Report, Vol. 59, No. 39, October 8, 2010.