Table 2.
Association of GSTM1-null, HLA-DRB1 shared epitope (SE) and smoking with ACPA positivity in rheumatoid arthritisa
| VARA (n = 703) | SONORA (n = 610) | |||||
|---|---|---|---|---|---|---|
| ACPA+ (%) |
OR (95% CI) | P value | ACPA+ (%) |
OR (95% CI) | P value | |
| GSTM1-present | 73 | Ref. | - | 69 | Ref. | - |
| GSTM1-null | 79 | 1.45 (1.02 to 2.05) | 0.039 | 69 | 1.00 (0.71 to 1.42) | 0.981 |
| Never smoking | 69 | Ref. | - | 69 | Ref. | - |
| Ever smoking | 78 | 1.48 (0.97 to 2.26) | 0.067 | 68 | 0.90 (0.62 to 1.30) | 0.574 |
| Former smoking | 77 | 1.41 (0.91 to 2.19) | 0.129 | 65 | 0.77 (0.52 to 1.14) | 0.193 |
| Current smoking | 81 | 1.68 (0.98 to 2.88) | 0.059 | 74 | 1.23 (0.76 to 1.99) | 0.407 |
| SE-negative | 53 | Ref. | - | 54 | Ref. | - |
| SE-positive (one or two alleles) | 84 | 4.36 (2.98 to 6.37) | < 0.001 | 75 | 2.56 (1.77 to 3.70) | < 0.001 |
| SE-positive (one allele) | 79 | 3.23 (2.17 to 4.81) | < 0.001 | 68 | 1.77 (1.21 to 2.60) | 0.003 |
| SE-positive (two alleles) | 93 | 10.65 (5.61 to 20.20) | < 0.001 | 92 | 10.27 (5.05 to 20.89) | < 0.001 |
aACPA, anticitrullinated protein antibody; CI, confidence interval; GSTM1, glutathione S-transferase Mu-1; OR, odds ratio; SE, shared epitope; SONORA, Study of New-Onset Rheumatoid Arthritis; VARA, Veterans Affairs Rheumatoid Arthritis Registry. All analyses are age- and gender-adjusted. "Ref." = referent group in each analysis.