Prevalence and impact of arthritis

Arthritis affects nearly 50 million adults in the USA and is projected to increase in prevalence to 67 million adults, or 25% of those aged 18 years and older, by the year 2030 (Centers for Disease Control and Prevention, 2010a).

Arthritis is associated with significant healthcare and cost burden on society. In the USA alone, arthritis results in about 1 million annual hospitalizations (Helmick et al., 2008) and 44 million annual outpatient visits (American Academy of Orthopedic Surgeons, 2008). In 2003, the total cost of arthritis was $128 billion in the USA, including $81 billion in direct medical costs and $47 billion in indirect costs (lost earnings) (Centers for Disease Control and Prevention, 2007). Osteoarthritis alone is responsible for between $3.4 and $13.2 billion job-related costs each year (Buckwalter et al., 2004; Centers for Disease Control and Prevention, 2010b). Consequently, arthritis constitutes a public health problem associated with significant socioeconomic burden.

Osteoarthritis is the most common type of non-inflammatory arthritis that affects the aging population, but it can also present at a younger age in those with trauma or obesity. It primarily affects hands, knees and hips but can be generalized and affect other joint areas. It is characterized by cartilage lesions leading to symmetric narrowing of joint space, overproduction of bone leading to osteophytes and bony deformities. Inflammatory arthritis is characterized by swelling of the joint lining, which leads to joint destruction and bony erosions when not optimally treated. Two common types of inflammatory arthritis are rheumatoid arthritis and gout, which have predilection for different joints and have a different pathophysiology. Both are also associated with significant joint swelling, warmth and tenderness.