Arthritis is the most common chronic disease affecting joints and is also the most common cause of disability in the United States. Many forms of arthritis are also life-threatening. While it has been tempting to speculate that arthritis will become more common as the Baby Boom generation continues to age, there has been a relative lack of hard data to support that notion.

The National Arthritis Data Workgroup is a consortium of epidemiologic experts who have collected and analyzed information from various sources to provide an assessment of the state of arthritis now and the potential implications for the future.

Key findings of the group were published recently (Helmick CG, Felson DT, Lawrence RC, Gabriel S, Hirsch R, Kwoh CK, Liang MH, Kremers HM, Mayes MD, Merkel PA, Pillemer SR, Reveille JD, Stone JH, Arnold LM, Choi H, Deyo RA, Hochberg MC, Hunder GG, Jordan JM, Katz JN, and Wolfe F. Arthritis & Rheumatism. 2008; 58:1)

Among the findings include:

Twenty-one percent of U.S. adults (more than 46 million people) have arthritis or related conditions. Approximately, two-thirds of arthritis patients are younger than 65. More than 60 percent are female. Disease rates are similar for whites and African-Americans and both have arthritis rates that are higher than the rates for Hispanics.

By 2030, the number of people with arthritis is projected to increase to nearly 67 million--an increase of 40 percent.

Osteoarthritis (OA) is the most common form of arthritis. It is a degenerative condition where the cartilage, the gristly that covers the ends of long bones begins to prematurely wear away. OA occurs most commonly in weight-bearing joints such as the neck, low back, hips, and knees. It may also affect the hands, most commonly the base of the thumbs, as well as the base of the great toe. Nearly 27 million Americans suffer from osteoarthritis, an increase from the 21 million found in 1990.

Rheumatoid arthritis (RA) is another common type of arthritis. It is a chronic, systemic, progressive, autoimmune disease that affects 1.3 million adults. This last figure was a surprise because the 1990 estimate was 2.1 million. The reasons for this decline include the use of more-restrictive classification criteria as well as what appears to be a real drop in prevalence.

Trends also indicate that the average age of diagnosis has increased steadily over time, showing that RA is becoming a disease of older adults.

Gout is a chronic inflammatory form of arthritis that is due to deposits of uric acid within joints that induce inflammation. Gout also adversely affects kidney function. This disease, according to this recent study, afflicts 3 million Americans. This number is up from the estimate of 2.1 million in 1990. Gout is more common in older men. It appears to affect African American males more than whites or Hispanics.

The spokesperson for the Task Force, Dr. Charles G. Helmick, acknowledged the difficulty with providing meaningful statistical estimates. He reminded readers that some forms of arthritis are episodic and others have no standard case definition.

Also, estimates for some arthritic conditions rely on older studies with results that are not necessarily applicable to the current U.S. population.

Recognizing these shortcomings, the study still calls attention to the high prevalence of arthritis and the growing burden on the health care system and on society in general.

While the incidence of arthritis is increasing, research efforts aimed at finding newer, more effective treatments will hopefully keep up pace so that the profound physical and societal impact of arthritis is lessened.