Arthritis affects approximately 500,000 Irish men and women and over 5,000 Irish children under the age of 12. There are over 100 types of arthritis.

Rheumatoid arthritis (RA) is a chronic, auto-immune, inflammatory disease mainly affecting the joints. It affects approximately 1 percent of the Irish adult population, over 80 percent of whom develop the disease between the ages of 35 and 50. RA is significantly more prevalent in women than in men, with the overall ratio about three women to one man.

To understand how RA affects the joints, it is helpful to know how a normal joint works. Put simply, a joint is where two bones meet. To allow the bones to move against each other without friction, each bone is covered with cartilage, which has a smooth slippery surface. The joint is surrounded by a membrane (the synovium). The synovium produces a thick fluid called synovial fluid, which acts as a lubricant to help the joints move smoothly.

In RA the synovial membrane of the joints is persistently inflammed. Inflammation is a normal response produced by the body's immune system to fight off infection and heal injury. The inflammatory reaction is self-limiting and works to the benefit of the body.

In RA the inflammation in the synovial membrane does not subside in the normal manner, instead it persists. The synovial membrane becomes thickened and protrudes into the joint resulting in destruction of the cartilage and erosion of bone.

This inflammation process may eventually result in the joint becoming deformed. The muscles, ligaments and other soft tissue around the joint are also weakened. Combined with the deformity, this reduces the function of the joint.

RA is a multi-system or systemic disease, meaning it can affect all of the body systems.

What causes RA?

The cause of RA is unknown. While a person's genetic make-up can predispose them to developing RA (research suggests RA is four times more likely to develop in first degree relatives than in the general public), the most common theory is that RA develops in a susceptible person in response to trigger factors, such as an infectious agent.

It is possible that part of the infectious agent remains in the synovial membrane, generating a chronic inflammatory reaction. Another theory is that the infectious agent's structure is similar in make-up to the tissue or cell in joint tissue, or that it alters the structure of the tissue so the immune system recognises it as foreign material and attacks the synovial membrane. This is known as an autoimmune reaction.

There are a number of other theories as to the cause of RA including loss of normal self-tolerance leading to inappropriate stimulation of the immune system against parts of the body or breakdown in the mechanisms that control inflammation.

What are the typical symptoms of RA?

RA may develop slowly over weeks and months or it may present quickly. The severity of the disease is also very variable. In 20 percent of cases RA is mild in nature, with few joints involved and there is little residual damage to joints. However, in about 10 percent of cases the disease is very severe, affecting many joints and causing marked deformity. The majority of cases chart an intermediate course.

Early in the disease, symptoms may include:

• Pain, swelling and stiffness in the joints;
• Joints are tender to touch;
• Reduced mobility of the joint -initially due to pain and later to joint deformity;
• Morning stiffness - the joints are stiff in the morning and this often lasts more than hour;
• Fatigue;
• Loss of appetite;
• Weight loss;
• Fever;
• Swollen lymph glands;

 Later in the disease process, symptoms may include joint deformity:

• affected fingers and toes may be permanently bent (contractures);
• hands and feet may curve outwards

Which joints are affected?

RA can affect any of the joints. In the majority of cases, there is symmetrical involvement of joints (i.e. both sides of the body, such as both hands, are affected). Early in the disease process, the most commonly affected joints are:


Joints      % of Cases
 
Hands            90
 
Feet                 90
 
Wrists             80
 

Other commonly affected joints include:

Joints       % of Cases
 
Ankles            80
 
Knees            80
 
Shoulder       60
 
Hip                 50
 
Elbow            50
 
Although RA mainly affects the joints, other systems in the body may be affected. Weakness and atrophy (breakdown) of muscles near affected joints are common in RA sufferers. Other symptoms occur only in severe cases and include rheumatoid nodules (lumps, of varying sizes, under the skin, mainly found on the arms and legs; the achilles tendon and the back of the head), rheumatoid vasculitis (inflammation of the blood vessel walls) and osteoporosis (brittle bone disease).

How is RA diagnosed?

There is no specific test available for diagnosing RA. Apart from a history of the symptoms outlined above, your GP may check for:

• A High Rheumatoid Factor. Rheumatoid factor, a blood protein produced by a reaction in the immune system, is elevated in more than 66 percent of patients with RA. However, it is not specific for RA and is elevated in other auto-immune diseases and in 5 percent of the normal healthy population (this increases to 10-20 percent of individuals over 65 years.)

• A High ESR (Erythrocyte Sedimentation Rate). ESR is the rate at which the red cells in a column of blood fall. It is a non-specific test indicating the presence of disease.

•  Anaemia.

• Abnormal synovial fluid (produced by the synovial membrane to lubricate the joint). It may be straw coloured, contain a large number of white blood cells, lower than normal glucose level and increased protein. These changes are characteristic of joint infection from any cause.

What can I do to relieve the pain?

Treatment is aimed at relieving symptoms, preventing deformity and maintaining normal function. Exercise, physiotherapy and dietary advice are an important part of treatment.

Treatment with drugs that slow joint destruction and reduce disability (disease modifying antirheumatic drugs, or DMARDS) are also used.

These drugs need between four weeks and three months to take effect. Nonsteroidal anti-inflammatory drugs have no effect on long-term disability but do relieve pain and reduce inflammation. Corticosteroids are also used. Surgery may eventually be required to reduce joint deformity or replace damaged joints e.g. hip replacement.

Many drugs used in the treatment of RA have side-effects. For more information on these drugs speak to your GP. The Arthritis Foundation of Ireland also has some very informative free leaflets.