RHEUMATOID ARTHRITIS RISK FACTORS 

The specific cause of rheumatoid arthritis  is not known. Researchers suspect  that two  types of factors affect a person's risk: susceptibility factors and initiating factors. 

Rheumatoid  arthritis most likely occurs when a susceptible person is exposed to factors that start the inflammatory process. Approximately 1  in every 100 individuals has rheumatoid arthritis. 

Gender, heredity, and genes largely determine a person's risk  of developing rheumatoid arthritis. 

Gender  — Gender appears to play a major role in a person's susceptibility to rheumatoid arthritis. Women are about three times more likely than men to develop rheumatoid arthritis. 

Heredity  — Rheumatoid  arthritis is not an inherited disease. Genes do not cause rheumatoid arthritis, they merely increase the risk  of its development. 

Specific genes  — People  with specific human leukocyte antigen (HLA) genes are more likely to develop rheumatoid arthritis than people without these genes. 

Initiating factors  — Many individuals who carry HLA genes never develop the condition. Indeed, when one identical twin has rheumatoid arthritis, the chance that the other will develop disease is only about 1 in 3. This suggests that additional factors must be necessary for  a person to develop RA. 

Infection  — Researchers suspect that infection with bacteria  or viruses may be one of the factors that initiates rheumatoid arthritis. However, at this time, there is no definite evidence linking infection to rheumatoid arthritis.
Cigarette smoking — Cigarette smoking may increase the risk of developing rheumatoid arthritis. There is also some evidence that cigarette smoking increases the likelihood that rheumatoid arthritis will be severe when it occurs. 

Stress  — Patients often report episodes of stress or trauma preceding the onset of their rheumatoid arthritis. Stressful "life events" (divorce, accidents, grief, etc) are more common in people with RA in the six months before their diagnosis compared to the general population. 

RHEUMATOID ARTHRITIS SYMPTOMS 

In most people, rheumatoid arthritis begins insidiously, and weeks or months may pass before the characteristic  symptoms are bothersome enough to cause a person to seek medical care. Early symptoms  may include fatigue, muscle pain, a low-grade fever, weight loss, and numbness and tingling in the hands. In some cases, these symptoms occur before joint pain or stiffness are noticeable. 

Occasionally, rheumatoid arthritis begins with symptoms related to inflammation  of tissues other than the joints. For example, a person may experience chest pain or shortness of breath. 

Pattern of joints affected  — Rheumatoid arthritis usually affects the same joints on both sides of the body.
In the early stages, rheumatoid arthritis typically affects small joints, especially the joints at the base of the fingers, the joints in the middle of the fingers, and the joints at the base of the toes. It may  also begin in a single, large joint, such as the knee or shoulder, or it may come and go and move from one joint to another. 

As the condition progresses, most people  have inflammation  of the joints in the arms or legs, and between 20 to 50 percent of people have inflammation of the large central joints (eg, hips) and spine. 

Joint symptoms — The joint symptoms of rheumatoid arthritis usually begin gradually and include pain and  stiffness, redness, warmth to the touch, and joint swelling. 

The joint stiffness is most bothersome in the morning and after sitting still for a period of time. The stiffness can persist for more than one hour. 

Hands  — The joints of the hands are often the very first joints affected by rheumatoid arthritis. These joints are tender  when squeezed, and the hand's grip strength is often reduced. Occasionally, rheumatoid arthritis may lead to visible redness and swelling of the entire hand. 

Between 1 and 5 percent of people with rheumatoid arthritis develop carpal tunnel syndrome because swelling compresses  a nerve that runs through the wrist; this syndrome is characterized by weakness, tingling, and numbness of certain areas of the hand. 

Certain characteristic hand deformities can occur with long-standing rheumatoid arthritis. The fingers may develop characteristic, exaggerated profiles, called swan neck deformities and boutonniere deformities, and may drift together in the direction of the small finger. This photograph depicts ulnar drift in  a person with mixed connective tissue disease, although the appearance is similar in people with RA (picture 1). The tendons on the back of the hand may become very prominent and taught, called the bow string sign. 

Wrist  — The wrist is the most commonly affected  joint of the arm in people with rheumatoid arthritis. In the early stages of rheumatoid arthritis, it may become difficult to bend the wrist backward; in later stages, the bones of the wrist may slip out of their joints, causing the hand to bend toward the small finger. 

Elbow  — Rheumatoid arthritis may cause inflammation of the elbow. Swelling of this joint may compress nerves that travel through the arm  and cause numbness or tingling  in the fingers.

Shoulder — The shoulder may be inflamed in the later stages  of rheumatoid arthritis, causing pain and limited motion. 

Foot  — The joints of the feet are often affected in the early stages of rheumatoid arthritis, especially the joints at the base of the toes. Tenderness at  these joints may cause a person to stand and walk with his  or her weight on the heels, with the toes bent upward. The top of the foot may be swollen and red and, occasionally, the heel may be painful. 

Ankle  — Rheumatoid arthritis may cause inflammation of the ankle. Inflammation of this joint may cause nerve damage, leading to numbness and tingling in the foot. 

Knee  — Rheumatoid arthritis may cause swelling of the knee, difficulty bending the knee, excessive looseness of the ligaments that surround and support the knee, and damage of the ends of the bones that meet at the knee. Rheumatoid arthritis may also cause the formation of  a Baker's cyst (a cyst filled with joint fluid and located in the hollow space at the back of the knee). 

Hips  — The hips may become inflamed in the later stages of rheumatoid arthritis. Pain in the hips may make it difficult to walk. 

Cervical spine  — Rheumatoid arthritis may cause inflammation of the cervical spine, which is the area between the shoulders and the base of the head. Inflammation of the cervical spine may cause  a painful and stiff neck and  a decreased ability to bend the neck and turn the head. 

Cricoarytenoid joint  — In  about 30 percent of people with rheumatoid arthritis, there is inflammation of a joint near the windpipe called the cricoarytenoid joint. Inflammation of this joint can cause hoarseness and difficulty breathing. 

Other  symptoms — Although joint problems are the most commonly known issues in rheumatoid arthritis, the condition can be associated with a variety of other problems. 

Rheumatoid nodules  — Rheumatoid nodules are painless lumps that appear beneath the skin. These nodules may move easily when touched or they may be fixed to deeper tissues. They most often occur on the underside of the forearm  and on the elbow, but they can also occur on other pressure points, including the back of the head, the base of the spine, the Achilles tendon, and the tendons of the hand. 

Inflammatory conditions  — Rheumatoid arthritis may produce  a variety of other symptoms, depending on which tissues are inflamed. 

• Inflammation of the tissue lining the chest cavity and surrounding the heart) may cause chest pain and difficulty breathing. 
• Inflammation of the lung that is not due to infection may cause shortness of breath and a dry cough. 
• Abnormal nerve function may cause numbness, tingling,  or weakness. 
• Inflammation of the white part of the eye  may cause vision problems. 
• Enlargement of the spleen may cause a fall in the number of white blood cells, which may lead to infections. 
• Sjögren's syndrome causes dry eyes and dry mouth, which can lead to a gritty feeling  or a sensation of irritating material in the eyes. Mouth dryness may make it difficult to chew or swallow without drinking something at the same time. Women may develop vaginal dryness due to Sjögren's syndrome, leading to pain with sexual intercourse. 
• Vasculitis (inflammation of the blood vessels) may cause a wide variety of symptoms, depending upon where the inflamed blood vessels are located.