Rheumatoid arthritis is a type of disease known as an autoimmune disease – that is, a disease caused by the body’s own immune system. In rheumatoid arthritis, the immune system attacks the membrane lining the joints. This causes inflammation, which leads to pain, stiffness and swelling of the affected joints.

Rheumatoid arthritis is not the same as osteoarthritis, the most common form of arthritis, which people often just call ‘arthritis’. Osteoarthritis, or OA, is caused by general wear and tear of the joints and is very common as people get older. In osteoarthritis, cartilage (a spongy substance that cushions the joints and stops bones rubbing against each other when they move) becomes stiff and damaged until eventually, it may wear away completely. This leads to bone damage, inflammation, pain and stiffness. The treatment of osteoarthritis is aimed at reducing the pain and inflammation and is different from the treatment for rheumatoid arthritis

Epidemiology of rheumatoid arthritis

In Europe and North America, rheumatoid arthritis affects 0.5–1% of the population in total. However, it is much more common in Native Americans (affecting over 5%) and less common in African and Asian people. This suggests that there are genetic factors involved in the development of the disease.

Gender

Women are two-to-three times more likely than men to develop rheumatoid arthritis. The exact cause for this is not known, but it may be related to the hormone, oestrogen

Age

Rheumatoid arthritis can develop at any age but it is more common in older people. It is most likely to be diagnosed in people between 40 and 60 years of age.

Family history

Although rheumatoid arthritis is not a hereditary disease, certain genes can make a person more susceptible to it. This means that people with close relatives who suffer from rheumatoid arthritis have a higher than usual risk of developing it themselves because they may have inherited the same genes. However, they are still more likely not to get the disease than to get it.

Smoking

People who smoke have a higher risk of developing rheumatoid arthritis than those who do not.

Epidemiology of rheumatoid arthritis

In Europe and North America, rheumatoid arthritis affects 0.5–1% of the population in total. However, it is much more common in Native Americans (affecting over 5%) and less common in African and Asian people. This suggests that there are genetic factors involved in the development of the disease.

Effects of rheumatoid arthritis

Rheumatoid arthritis is a variable disease that affects people differently. The symptoms can come and go, with flare-ups and periods of remission. This means it is difficult to predict how the disease will affect a particular individual.

Pain is the most problematic symptom for people with rheumatoid arthritis but they may also feel tired and generally unwell. These symptoms can be difficult for other people to understand. For some sufferers, symptoms may be fairly mild and not interfere too much with their usual daily life and work. For others, the symptoms may be more severe and they may find it difficult to get around and perform everyday tasks such as dressing or bathing. Work, relationships and emotional state can all be affected. Lifestyle changes, physiotherapy and occupational therapy can help overcome some of these difficulties.

History of rheumatoid arthritis

Rheumatoid arthritis is not just a disease of the modern world. Signs of rheumatoid arthritis have been noted in skeletal remains from as long ago as 4500BC and an Indian text from 123AD provides the first written account of symptoms suggestive of rheumatoid arthritis.

Rheumatism was first described in the late sixteenth century by a French physician, Guillaume de Baillou, as pain originating from the tissues, muscles, tendons, bones and joints. The term ‘rheumatoid arthritis’ was coined by British physician Sir Alfred Garrod in 1859.

Although the exact cause of rheumatoid arthritis is still not known, the autoimmune nature of it was recognised in 1939 by an Australian researcher named Sir McFarlane Burnet. This was supported by the discovery of rheumatoid factor (an antibody that is commonly found in the blood of patients with rheumatoid arthritis), also in 1939, by Dr Eric Waaler. A test for rheumatoid factor was developed in 1948 by Dr HM Rose and colleagues. Testing for rheumatoid factor is still used to help diagnose rheumatoid arthritis today.

Types of rheumatoid arthritis

Rheumatoid arthritis can be classified into different subtypes, depending on the genes and molecules involved in the disease process. However, subtyping involves complicated genetic testing and is not performed routinely since it does not affect the diagnosis or treatment of the disease. Subtyping is performed occasionally for research purposes.

Juvenile rheumatoid arthritis is distinct from the adult form. It develops in children under the age of 16 years and can take one of three subtypes:
Pauciarticular juvenile rheumatoid arthritis

This is the most common form of juvenile rheumatoid arthritis, accounting for 40–60% of cases. Symptoms affect no more than four joints initially, although more may be involved later in the course of the disease. The most commonly affected joints are the knees, ankles, wrists or elbows. It is the least severe form of juvenile rheumatoid arthritis.
Polyarticular juvenile arthritis

This accounts for around 40% of cases of juvenile rheumatoid arthritis and is more common in girls than boys. Symptoms develop in five or more joints, often the small joints of the hands or feet although larger joints can be affected. Polyarticular juvenile arthritis is thought to be the same as the adult form of rheumatoid arthritis but occurring at a very young age.
Systemic onset juvenile rheumatoid arthritis

This is the least common form of juvenile rheumatoid arthritis, accounting for around 10% of cases. It tends to develop in children between 5 and 10 years old and presents with non-joint symptoms such as persistently high temperature, rash, loss of appetite and anaemia. Joint and muscle pain often develops later. Systemic onset rheumatoid arthritis can also cause symptoms in the heart, lung or eyes.

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