People with a family history of rheumatoid arthritis (RA) should be advised to give up smoking to try to avoid the disease, new study results suggest.
Smoking and genetic factors combine to increase the risk of RA. To clarify this relationship, Henrik Källberg of Sweden’s Karolinska Institute analyzed data from 1,204 clinic patients with RA and 871 controls in southern and central Sweden. All participants answered questions about their smoking habits and provided blood samples.
More than half of the persons with RA tested positive for anticitrullinated protein/peptide antibody (ACPA), representing the most severe and most common form of the disease. Those who had smoked at least 20 cigarettes a day for at least 20 years—the heaviest smokers—were more than 2.5 times as likely to test positive for ACPA. Former smokers ran less of a risk as more time passed since they last smoked. However, the risk was still relatively high among the heaviest smokers, even if they hadn’t smoked for two decades.
As reported in Annals of the Rheumatic Diseases (published online ahead of print), smoking appeared to be responsible for an estimated 35% of ACPA-positive cases of RA and one in five RA cases overall. Further, the habit also accounted for 55% of RA cases among persons who were genetically susceptible to RA and who tested positive for ACPA, with the heaviest smokers carrying the highest risk.
A different team of Karolinska investigators recently discovered that current smokers with early RA are less likely than never-smokers to achieve good responses to methotrexate and tumor necrosis factor inhibitor (Arthritis Rheum. 2011;63:26-36)