Rheumatoid arthritis risk increases with smoking

A Swedish study finds that women smoking as little as one to seven cigarettes a day more than double their risk of developing rheumatoid arthritis.

Even a few cigarettes a day can increase the risk of rheumatoid arthritis in women.

Women who smoke cigarettes may find it is too painful to pick up a pack in the future.

A Swedish study finds that women smoking as little as one to seven cigarettes a day more than double their risk of developing rheumatoid arthritis, the painful autoimmune disease that causes inflammation in the joints of one per cent of Canadians.

The researchers from the Karolinska Institute in Stockholm found that duration of cigarette smoking was also an important risk: women who smoked for more than 25 years had twice the risk of developing rheumatoid arthritis than women who have never smoked.

And contrary to previous studies, head researcher Daniela Di Giuseppe and team found that the risk of developing the debilitating disease remained elevated for ex-smokers as long as 15 years after they quit. This difference in findings may be due to the fact that Di Giuseppe considered how many packs the women smoked a year.

The study, published this week in the journal Arthritis Research & Therapy, surveyed 34,101 women between the ages of 54 and 89 about their smoking habits. Over half of the women said they had never smoked cigarettes. The remaining 46 per cent of the cohort answered questions about when they started smoking, how many cigarettes they smoked a day, and the years since they quit smoking.

Only 219 women in the study had rheumatoid arthritis, but 60 of them were former smokers and 80 were current smokers. Both former and current smokers with rheumatoid arthritis were generally younger than the women with rheumatoid arthritis who had never smoked.

Prevalence of rheumatoid arthritis is almost twice as high in Canada than in the population of this study, according to Statistics Canada.  It's estimated that 300,000 Canadians suffer from the disease.

Rheumatoid arthritis commonly begins affecting women between 25 and 50 years old, but it can affect men and women of any age. The study did not look at the association between younger women or men and the risk of developing rheumatoid arthritis.

Dr Kathy Siminovitch, a Senior Investigator at Samuel Lunenfeld Research Institute of Mount Sinai Hospital  in Toronto, who studies the development of autoimmune diseases like rheumatoid arthritis, said Monday that Di Giuseppe’s study is "very believable" because it was done on a large, representative population.

"There are some papers prior to this that provide really strong epidemiological evidence that smoking does increase the risk" of rheumatoid arthritis said Siminovitch.

The exact link between smoking and developing rheumatoid arthritis remains unclear. But Siminovitch says that we are getting a lot closer to understanding what genetic factors cause rheumatoid arthritis to develop. "If we use the genetic information we have right now, we'll be pretty able to predict those who are at high risk. We're just on the verge of that right now."