ORs of developing ACPA-positive RA for subjects exposed to OC and ever smoking/HLA-DRB1 SE alleles/PTPN22 in women aged 18 years or above. EIRA, Sweden, 1996–2014
| Ever | Never | 358/1205 | 1.0 | 1.0 |
| Never | Never | 201/684 | 1.05 (0.86 to 1.28) | 0.99 (0.81 to 1.21) |
| Ever | Ever | 771/1632 | 1.61 (1.39 to 1.87) | 1.71 (1.47 to 1.99) |
| Never | Ever | 364/563 | 2.33 (1.94 to 2.80) | 2.34 (1.95 to 2.82) |
| AP§ | – | – | 0.29 (0.15 to 0.43) | 0.28 (0.14 to 0.42) |