Rheumatoid arthritis (RA) is an autoimmune disease in which progressive damage to the joints leads to increasing disability. It is characterized by painful and inflamed joints. The immune system attacks components of the joints, grossly deforming and destroying cartilage, bone and tendons, causing the joints to lose their function. RA can show an abrupt onset (10% of cases), but more often the disease has a slow and insidious course. Whilst it goes naturally into remission from time to time, generally it is an extremely disabling disease that carries a high mortality.
It has been claimed that about 30-40% of rheumatoid arthritis suffers are sensitive to dietary therapy, particularly the exclusion of cereals and inclusion of fish oils known as omega-3 marine triglycerides (the latter can reduce inflammation of the joints although they are no more effective than many of the anti-inflammatory drugs commonly used).
Between 0.5% and 2% of the world's population have rheumatoid arthritis. In the USA the incidence is approximately 3% of the population, mostly women. Rheumatoid arthritis affects 2.5 million people in the UK. As an indication, the market for topical analgesics (for muscular aches and pains) in the UK in 1986 was £10.2 million.
Although autoimmune arthritis can afflict children and adolescents, the disease usually strikes adults between the ages of 30 and 40, and the incidence of clinical illness is greatest among those aged 40 to 60 years. Even with appropriate drug therapy, up to 7% of patients are disabled to some extent 5 years after disease onset, and 50% are too disabled to work 10 years after disease onset.
People with a long history of heavy smoking are more likely than nonsmokers to develop rheumatoid arthritis. In a US study, people who smoked a pack of cigarettes a day for more than 40 years were 13 times more likely than nonsmokers to develop rheumatoid arthritis. The researchers conclude that although smoking itself is not associated with rheumatoid arthritis, prolonged heavy smoking is a risk factor. When such a relationship is found, it is often difficult to say which came first: do people with rheumatoid arthritis smoke more because they have the disease, or do people who smoke heavily tend to get the disease because they smoke? One plausible connection is the effect of smoking on the body's production of rheumatoid factor – antibodies often found in the blood of rheumatoid arthritis patients. Heavy exposure to smoke over time increases the production of rheumatoid factor among both healthy people and those with rheumatoid arthritis.