Odds ratios for developing ACPA-positive RA and ACPA-negative RA in subjects exposed to different combinations of smoking and presence of HLA-DRB1*04:05 or non-HLA-DRB1*04:05 SE alleles, compared with never-smokers without SE alleles in MyEIRA. Here, HLA-DRB1 is linked to rheumatoid arthritis.