Female smokers' arthritis risk
Smoking just a few cigarettes a day can more than double a woman's risk of rheumatoid arthritis, research has shown.
Compared with those who have never smoked, women who puffed between one and seven cigarettes a day had a 2.31-fold higher chance of developing the disease.
Even 15 years after quitting, the risk was nearly twice as high among former smokers.
But the study did find that the likelihood of suffering rheumatoid arthritis reduced over time after giving up smoking.
Researchers in Sweden analysed data from 34,101 women aged 54 and 89, of whom 219 had rheumatoid arthritis (RA).
RA is an autoimmune disease caused by the body's immune system attacking the joints. It differs from osteoarthritis, which is the result of wear and tear and damage from injuries.
The study also found that RA risk increased with the length of time a woman had been smoking.
The findings are published in Arthritis Research & Therapy.