Table 3.
Association of smoking or HLA-DRB1 SE and anti-CPP3 IgG in pre-symptomatic individuals compared with controls adjusted for age and sex
| Anti-CPP3 IgG | Pre-symptomatic individuals, n (%) | Controls, n (%) | OR (95 % CI) | |
|---|---|---|---|---|
| Smokinga | ||||
| – | – | 84 (33.6) | 90 (49.7) | Reference |
| + | – | 149 (59.6) | 85 (47.0) | 2.12 (1.39–3.23) |
| – | + | 6 (2.4) | 2 (1.1) | 3.01 (0.58–15.47) |
| + | + | 11 (4.4) | 4 (2.2) | 2.83 (0.86–9.40) |
| HLA-DRB1 SEb | ||||
| – | – | 79 (31.6) | 107 (62.6) | Reference |
| + | – | 154 (61.6) | 59 (34.5) | 3.55 (2.32–5.42) |
| – | + | 6 (2.4) | 3 (1.8) | 2.41 (0.58–10.13) |
| + | + | 11 (4.4) | 2 (1.2) | 6.74 (1.43–31.81) |
| RERI = 2.21 (−8.13, 29.19), AP = 0.30 (−3.22, 0.55), SI = 1.52 (0.22–10.90), MI = 0.77 (0.10–6.29), p value = 0.81 | ||||
aDefined as ever smoker
b HLA-DRB1 shared epitope (SE) defined as 0101/0401/0404/0405/0408
OR odds ratio, CI confidence interval, RERI relative excess due to interaction, AP attributable proportion due to interaction, SI synergy index, MI multiplicative interaction