Odds ratio (OR) with 95% CI of developing ACPA-positive RA, ACPA-negative RA and RA overall, respectively, among men with different combinations of silica exposure status and HLA-DRB1 ‘shared epitope’ (SE) status, compared with men unexposed to silica who were not carrying SE
| Subjects unexposed to silica | Subjects exposed to silica | ||||||
|---|---|---|---|---|---|---|---|
| SE status | Category of RA | Number of cases/controls | OR* | 95% CI | Number of cases/controls | OR* | 95% CI |
| No SE | ACPA-positive RA | 35/165 | 1 | – | 8/16 | 2.51 | 0.97 to 6.49 |
| ACPA-negative RA | 80/165 | 1 | – | 6/16 | 0.84 | 0.31 to 2.27 | |
| RA overall | 119/165 | 1 | – | 14/16 | 1.32 | 0.61 to 2.86 | |
| Any SE | ACPA-positive RA | 238/142 | 7.86 | 5.10 to 12.12 | 46/21 | 11.39 | 5.10 to 22.07 |
| ACPA-negative RA | 103/142 | 1.52 | 1.04 to 2.23 | 13/21 | 1.46 | 0.67 to 3.20 | |
| RA overall | 368/142 | 3.54 | 2.59 to 4.83 | 63/21 | 4.45 | 2.53 to 7.83 | |
↵* OR adjusted for the potential confounding from age and residential area.
ACPA, antibodies against citrullinated peptide antigens; RA, rheumatoid arthritis.