Smoking Combined with Genetics Linked to Rheumatoid Arthritis

Everyone knows that smoking is not healthy, but recent studies show that, when combined with certain genetic factors, it could be linked to the detrimental disease rheumatoid arthritis (RA).

Smoking has been found to increase the risk of RA in people who have a family history of the disease. Henrik Källberg of Sweden's Karolinska Institute evaluated data from 1,204 clinic patients who live with RA and 871 people in a control group in southern and central Sweden. Each participant gave a response to questions concerning his or her smoking habits. Blood samples were also provided from these partakers.

The study showed that more than 50 percent of the participants living with RA tested positive for anti­citrullinated protein/peptide antibody (ACPA), which corresponds with the most severe and most widespread form of RA. The participants who were the heaviest smokers, or people who had smoked at minimum 20 cigarettes per day for at least 20 years, were more than 2.5 times as probable to test positive for ACPA.

Former smokers were less likely to test positive for ACPA, which increased corresponding to the time passed since they last smoked. The risk was still relatively high, however, among participants who would formerly have qualified as the heaviest smokers, despite the fact that some had not smoked for as long as two decades.

The journalAnnals of the Rheumatic Diseases (published online ahead of print) reported that smoking appeared to be responsible for an anticipated 35% of ACPA-positive cases of RA and 1 in 5 cases of RA overall. Additionally, smoking also accounted for 55% of RA cases among people who had a family history of RA and who tested positive for ACPA, with the heaviest smokers carrying the largest risk.

Further, a team of Karolinska investigators separate from this particular study recently discovered that current smokers experiencing the onset of RA have less of a chance than never-smokers to attain positive responses to methotrexate and tumor necrosis factor inhibitor.