| Anti-CCP+ | Anti-CCP– | OR (95% CI) | |
| SE/SE | 81 | 7 | 5.2 (2.0 to 13.6) |
| SE/X | 98 | 32 | 1.1 (0.7 to 2.9) |
| X/X | 38 | 18 | 1 (–) |
| S2/S3P | 54 | 4 | 5.8 (1.8 to 18.6) |
| S2/S2 | 14 | 2 | 2.8 (0.6 to 13.6) |
| S3P/S3P | 13 | 1 | 4.3 (0.5 to 35.6) |
| S2/L | 46 | 11 | 1.9 (0.8 to 4.6) |
| S3P/L | 52 | 21 | 1.2 (0.5 to 2.5) |
| L/L | 38 | 18 | 1 (–) |
Anti-CCP+, presence of anti-CCP antibodies; anti-CCP–, absence of anti-CCP antibodies; S2, HLA-DRB1*0401,*1303; S3p, *0101,*0102,*0404,*0408,*1001; L, all other HLA-DRB1 alleles.