Table 2.
Adjusted relative risks of RA by parity and HLA alleles
| Controls | Cases | ||||
| (N = 571) | (N = 310) | ||||
| N (%) | N (%) | RRa | 95% CI | p-value | |
| Parity | |||||
| Subjects < 45 years | |||||
| Nulliparous | 110 (33) | 82 (49) | 1.0 | ||
| Parous | 222 (67) | 85 (51) | 0.53 | 0.34 – 0.82 | 0.005 |
| Subjects ≥ 45 years | |||||
| Nulliparous | 40 (17) | 15 (10) | 1.0 | ||
| Parous | 199 (83) | 128 (90) | 1.43 | 0.71 – 2.89 | 0.31 |
| DRB1*04 copies | |||||
| 0 | 389 (68) | 133 (43) | 1.0 | ||
| 1 | 158 (28) | 129 (42) | 2.38 | 1.73 – 3.29 | |
| 2 | 24 (4) | 48 (15) | 5.65 | 3.22 – 9.92 | <0.001b |
| SE copies | |||||
| 0 | 337 (59) | 103 (33) | 1.0 | ||
| 1 | 203 (36) | 141 (45) | 2.28 | 1.64 – 3.15 | |
| 2 | 31 (5) | 66 (21) | 6.52 | 3.92 – 10.85 | <0.001b |
| DERAA copies | |||||
| 0 | 420 (74) | 252 (81) | 1.0 | ||
| 1 | 138 (24) | 51 (16) | 0.64 | 0.44 – 0.91 | 0.01 |
| 2 | 13 (2) | 7 (2) | −c | ||
a
adjusted for age, race (Caucasian vs. not), education level (college or more vs. less than college) and marital status (married or living as married vs. other).
b
p-value represents test for trend across copy levels.
c
categories for 1 and 2 copies of DERAA were combined for comparison to no copies.