Causes

The causes of rheumatic disease vary depending on the type of disease, but most remain under investigation. Scientists believe the combination of genetics, lifestyle, and environmental factors contribute to the development of certain types of arthritis, however the importance of each factor differs with each type of arthritis. Scientists clearly understand the discrete cause of the following two forms of arthritis.

Gout is caused by excessive uric acid in the body resulting from a diet high in protein or alcoholic beverages, or improper kidney functioning.

Infectious arthritis, specifically Lyme disease, is caused by a bacterial organism, called a spirochete, known to be transmitted by a bite of an infected tick.

In osteoarthritis it is believed that excessive joint stress that results from repeated injury or inherited cartilage weakness may play a role. Hormonal differences are believed to play a role in conditions that occur more frequently among women. Additionally, in lupus, scleroderma, and rheumatoid arthritis, the combination of genetic factors that determine susceptibility, the influence of certain hormones, and environmental triggers are believed to be important.

Lower educational levels and income levels have been found to be associated with the development of arthritis, yet the mechanism by which these demographics factors influence the risk of developing arthritis are not precisely understood.

Several modifiable risk factors have been associated with an increased risk for developing different forms of arthritis and these will be discussed in more detail later in this training. These include:
• Obesity
• Joint Injuries
• Infections
• Certain occupations (e.g., heavy industry, farming, shipyard work, and jobs requiring repetitive knee bending)

The development of arthritis has also been linked to several risk factors that cannot be modified. Examples of the individual factors include being a woman of advancing age and having a genetic predisposition. Let's examine these further.

Gender • 60 percent of women older than 15 have some form of arthritis. • 26.4 million American women have arthritis • Arthritis is the leading chronic condition among women. • By 2020, 4.6 million women will have an arthritis-related disability.

Age • The risk of developing arthritis increases with age, although arthritis can also affect children and teenagers. • Approximately 50 percent of the elderly population have some type of arthritis.

Genetic Predisposition

• Certain genes have been linked to some forms of arthritis.
• Arthritis tends to run in families, yet can skip generations.
• Work to map human genes may result in medical advances in this area.