Description: May 3, 2007 -- As America ages, the number of U.S. arthritis patients will rise from about 46 million people today to 67 million in 2030, the CDC predicts.

Of those 67 million people with arthritis in 2030, arthritis will limit usual activities for 25 million people (37%), according to the CDC's projections.

Those estimates are based on a 2005 national survey of more than 326,000 U.S. adults who were asked if a doctor had ever diagnosed them with some form of arthritis and if arthritis limited their usual activities.

The CDC projected the survey's results onto U.S. Census predictions for 2030.

Obesity could make arthritis even more common, and new treatments might lower arthritis-related disability, but the CDC didn't include those possibilities in its projections.

The CDC says arthritis will likely rise nationwide by 2030 except in North Dakota, West Virginia, and Washington, D.C., where the population is expected to decline.

Fourteen states will have more than a 30% increase in