Smoking "causes one-third of the severe rheumatoid arthritis" (Telegraph)

Among people who are genetically predisposed to debilitating disease, it represents more than half of the cases, the Swedish study.

Rheumatoid arthritis is painful swelling of the joints, appears to be caused by the immune system of the Agency address. Often it starts to affect between 40 and 60 people and is three times more common among women than among men. About 400,000 people suffer from it in the UK.

The researchers Karolinska in Stockholm has asked 1,200 people with RA on their habits of smoking, as well as nearly 900 people without it. Both series were matched for age, gender and other factors.

They found that people who smoked heavily in their lives - at least 20 per day for at least 20 years - was more than two-and-a-half times positive for a type of antibody, called the antibodies to proteins and peptides anticitrullinated (CSPA), it is probably now closely linked to the most common form and severe RA

Based on this and other personalities, they calculated that smoking represents 35% of the ACPA positive RA and one-fifth of global disease.

Among those who were genetically susceptible to the disease, researchers concluded that smoking is responsible for more than half (55 percent) of positive cases APAC.

However, they found that all the heavier smokers, the risk of developing the RA diminished once someone discontinued smoking.

The report is published today (TUES) online in annals of British Medical Journal of the rheumatic diseases.

Jane Tadman, from Arthritis Research UK, commented: "we have also been known for some time that factors in lifestyle, such as smoking, eat a lot of red meat and drink large quantities of caffeine can also affect the risk of developing the disease."

"As there is little you can do about changing your genetic makeup, it seems sensible to reduce other that you effectively control more risk factors." "Quit would be an obvious way to do it."