What is Rheumatoid Arthritis? Rheumatoid arthritis or RA, is an autoimmune disease that affects approximately 400,000 people in Australia, according to the Australian Rheumatology Association. It attacks the synovium in the joints causing thickening, inflammation and unwanted tissue growth. The cause of RA is not known - it is thought that genetic inherited factors, environmental factors (such as smoking), dietary factors, and infections and reproductive hormonal factors could be possible causative factors. The first signs or symptoms that a patient might experience includes pain, swelling, morning stiffness, fatigue and limited movement of the affected joints. The presence of rheumatoid factor does not establish a firm diagnosis as only about 80% of people with RA test positive, while about 5% of people without the disease test positive. A rheumatoid factor test measures the amount of rheumatoid factor in the patient's blood. Rheumatoid factors are proteins produced by the immune system that can attack healthy tissue in the body.