Smoking increases rheumatoid arthritis susceptibility in individuals carrying the HLA–DRB1 shared epitope, regardless of rheumatoid factor or anti–cyclic citrullinated peptide antibody status

Abstract

We demonstrated that the combination of SE alleles and smoking is associated with RA susceptibility regardless of anti-CCP antibody or RF status, but that the combination shows stronger effects in anti-CCP-positive/RF-positive patients with RA than in anti-CCP-negative/RF-negative patients with RA. The SE-smoking interactions were present in anti-CCP-positive and RF-positive RA.