Two in every nine Americans, a total of 49.9 million adults, now suffer from doctor-diagnosed arthritis, the Centers for Disease Control and Prevention said Thursday. The number is growing by about 1 million per year and is expected to reach 67 million by 2030, the agency reported in its Morbidity and Mortality Weekly Report. The driving factor for the rise in arthritis patients appears to be obesity, the researchers said. Among those who are obese, one in three women and one in four men have been diagnosed with the disorder, roughly double the proportion among those whose weight is normal.
Obesity particularly plays a role in the onset of knee osteoarthritis, the most common form of the disorder. That leads to disability, total knee joint replacement and poor clinical outcomes after replacement. Arthritis of the knee and other joints is already disabling: about 42% of those with arthritis, or 21.1 million people, have their activities limited by arthritis. The total cost of medical and impaired activity to the U.S. economy is about $128 billion annually, the agency said.