Number of cigarettes smoked a day and the number of years a person has smoked both increase the risk of rheumatoid arthritis (RA), finds research in BioMed Central's open access journal Arthritis Research & Therapy. The risk decreases after giving up smoking but, compared to people who have never smoked, this risk is still elevated 15 years after giving up.
Researchers from the Karolinska Institutet and Karolinska University Hospital analysed data from the Swedish Mammography Cohort, which included 34,000 women aged between 54 and 89, 219 of which had RA. Results of the study showed that even light smoking is associated with an increased risk of RA - smoking 1 to 7 cigarettes a day more than doubled this risk. When the team compared people who had never smoked, to women who had smoked for up to 25 years, they found that the risk also increased with length of smoking.
Stopping smoking did decrease chances of developing RA, with the risk continuing to decrease over time - 15 years after giving up the risk of RA had decreased by a third. However, compared to people who had never smoked, this risk remained significantly higher at 15 years after giving up.
Daniela Di Giuseppe, who led this study, commented, "Stopping smoking is important for many health reasons, including the increased risk of RA for smokers. But the clearly increased risk of developing RA, even many years after giving up, is another reason to stop smoking as soon as possible, and highlight the importance of persuading women not to start at all."