Odds ratios for rheumatoid arthritis (rheumatoid factor positive, rheumatoid factor negative, and overall) among subjects exposed to silica overall and among those who had worked with rock drilling or stone crushing, compared with unexposed subjects
| Age group (years) | Subjects exposed to silica overall v unexposed | Subjects who had worked with rock drilling or stone crushing v unexposed | |||||
|---|---|---|---|---|---|---|---|
| No of exposed cases | OR* | 95% CI | No of exposed cases | OR* | 95% CI | ||
| *Adjusted for the potential confounding from age, residential area, and cigarette smoking. | |||||||
| CI, confidence interval; OR, odds ratio; RA, rheumatoid arthritis; RF, rheumatoid factor. | |||||||
| RF+ RA | 18 to 49 | 7 | 1.4 | 0.4 to 4.5 | 2 | 4.1 | 0.3 to 53.5 |
| 50 to 70 | 20 | 2.2 | 0.8 to 5.8 | 13 | 3.2 | 0.8 to 12.0 | |
| 18 to 70 | 27 | 1.9 | 0.9 to 4.0 | 15 | 3.5 | 1.1 to 11.2 | |
| RF− RA | 18 to 49 | 3 | 1.8 | 0.1 to 25.8 | 1 | 0.7 | 0.0 to 18.1 |
| 50 to 70 | 11 | 3.3 | 0.9 to 12.3 | 3 | 3.0 | 0.3 to 28.8 | |
| 18 to 70 | 14 | 2.1 | 0.8 to 5.1 | 4 | 1.7 | 0.3 to 9.3 | |
| Total RA | 18 to 49 | 10 | 1.6 | 0.6 to 4.4 | 3 | 2.6 | 0.4 to 18.1 |
| 50 to 70 | 31 | 2.7 | 1.2 to 5.8 | 16 | 3.3 | 1.1 to 10.1 | |
| 18 to 70 | 41 | 2.2 | 1.2 to 3.9 | 19 | 3.0 | 1.2 to 7.6 | |