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Smoking behind a third of severe rheumatoid arthritis cases

arthritis Another reason to quit

Smoking is behind more than a third of all cases of severe rheumatoid arthritis, research suggests.

It is also to blame for more than half of cases in people who are genetically predisposed to developing the debilitating condition, a Swedish study found.

Around 350,000 people in the UK are affected by rheumatoid arthritis (RA). It is an autoimmune disease which occurs when the body's immune system attacks the lining of the joints, causing them to become red, swollen, inflamed and painful. It is three times more common in women than men.

In the study, more than 1,200 Swedish men and women with RA, and 871 without the condition were questioned about their smoking habits. They were then grouped according to how long they had smoked.

Blood samples were also taken to measure levels of anticitrullinated protein/peptide antibody (ACPA), a marker for disease severity, and to assess the participants’ genetic profile for susceptibility to RA.

The findings showed that the heaviest smokers were more than 2.5 times as likely to test positive for ACPA. A heavy smoker was defined as someone who had smoked 20 cigarettes a day for at least 20 years.

Among those who had a genetic predisposition to the disease, and who tested positive for ACPA, smoking accounted for more than half the cases (55 per cent). Those who smoked the most had the highest risk.

They also found that the risk of RA fell for ex-smokers, the longer they had given up smoking. However, among the heaviest smokers, the risk was still relatively high, even after 20 years of not having smoked.

Based on these figures, the researchers calculated that smoking accounted for 35 per cent of ACPA positive cases, and one in five cases of rheumatoid arthritis, overall.

Although the risk of RA from smoking is not as high as for lung cancer, where smoking accounts for 90 per cent of cases, it is similar to that for coronary artery heart disease, said the researchers.

The researchers, from the Karolinska Institute in Stockholm, said other environmental factors may add to an increased risk of rheumatoid arthritis, including air pollutants and hormonal factors.

But they suggest that their findings are sufficient to prompt those with a family history of rheumatoid arthritis to be advised to give up smoking.

The findings are published in the journal Annals of the Rheumatic Diseases.

This article was published on Tue 14 December 2010

Image © Sebastian Kaulitzki -

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