OR of RA together with 95% CI among workers classified as exposed to different combinations of cigarette smoking and asbestos or silica compared with workers classified as never exposed (n=126 534).
| All RA cases | Seropositive RA | Seronegative RA | |||||
| Cases/controls | Median intensity for asbestos (fibre/cm3) and silica (mg/m3) | Median years since last occupation classified as exposed | Median pack-years | Adjusted OR (95 % CI)* | Adjusted OR (95 % CI)* | Adjusted OR (95 % CI)* | |
| Asbestos | |||||||
| Men | |||||||
| Never smoker/no asbestos exposure | 671/9583 | 1.0 | 1.0 | 1.0 | |||
| Never smoker/exposed to asbestos | 124/1250 | 0.10 | 35 | 0 | 1.2 (0.7 to 2.2) | 1.6 (0.8 to 3.2) | 0.8 (0.3 to 2.1) |
| Smoker/no asbestos exposure | 1480/14 450 | 0.00 | – | 16 | 2.2 (1.7 to 2.9) | 3.3 (2.4 to 4.4) | 1.0 (0.7 to 1.5) |
| Smoker/exposed to asbestos | 479/3375 | 0.10 | 35 | 20 | 3.0 (2.0 to 4.4) | 3.8 (2.4 to 6.1) | 2.0 (1.1 to 3.5) |
| Women | |||||||
| Never smoker/no asbestos exposure | 2725/35 680 | 1.0 | 1.0 | 1.0 | |||
| Never smoker/exposed to asbestos | 5/32 | 0.02 | 33 | 0 | 4.4 (0.4 to 48.8) | – | – |
| Smoker/no asbestos exposure | 4634/39 846 | 0.00 | – | 13 | 1.7 (1.5 to 1.9) | 2.0 (1.7 to 2.3) | 1.1 (0.9 to 1.3) |
| Smoker/exposed to asbestos | 12/107 | 0.02 | 32 | 21 | 0.8 (0.2 to 3.2) | 1.2 (0.3 to 4.7) | – |
| Men and women† | |||||||
| Never smoker/no asbestos exposure | 3396/45 263 | 1.0 | 1.0 | 1.0 | |||
| Never smoker/exposed to asbestos | 129/1281 | 0.10 | 35 | 0 | 1.1 (0.6 to 1.9) | 1.2 (0.6 to 2.2) | 0.9 (0.4 to 2.3) |
| Smoker/no asbestos exposure | 6114/54 296 | 0.00 | – | 13 | 1.8 (1.6 to 2.0) | 2.2 (1.9 to 2.4) | 1.0 (0.9 to 1.3) |
| Smoker/exposed to asbestos | 491/3482 | 0.10 | 35 | 20 | 2.4 (1.7 to 3.4) | 2.6 (1.8 to 3.8) | 2.0 (1.2 to 3.3) |
| Silica | |||||||
| Men | |||||||
| Never smoker/no silica exposure | 870/12 245 | 1.0 | 1.0 | 1.0 | |||
| Never smoker/exposed to silica | 151/1399 | 0.07 | 21 | 0 | 1.1 (0.6 to 1.9) | 1.3 (0.7 to 2.6) | 0.7 (0.3 to 1.7) |
| Smoker/no silica exposure | 2086/20 116 | 0.00 | – | 17 | 2.1 (1.7 to 2.6) | 3.0 (2.3 to 4.0) | 1.0 (0.7 to 1.4) |
| Smoker/exposed to silica | 527/3304 | 0.08 | 26 | 20 | 2.9 (2.0 to 4.3) | 4.1 (2.7 to 6.4) | 1.4 (0.8 to 2.5) |
| Women | |||||||
| Never smoker/no silica exposure | 2769/36 286 | 1.0 | 1.0 | 1.0 | |||
| Never smoker/exposed to silica | 13/166 | 0.10 | 29 | 0 | – | – | – |
| Smoker/no silica exposure | 4789/41 084 | 0.00 | – | 13 | 1.7 (1.5 to 2.0) | 2.0 (1.8 to 2.3) | 1.1 (0.9 to 1.4) |
| Smoker/exposed to silica | 51/366 | 0.10 | 29 | 19 | 2.2 (0.9 to 5.4) | 2.7 (1.0 to 6.9) | 1.3 (0.3 to 6.3) |
| Men and women† | |||||||
| Never smoker/no silica exposure | 3640/48 532 | 1.0 | 1.0 | 1.0 | |||
| Never smoker/exposed to silica | 164/1565 | 0.07 | 25 | 0 | 0.8 (0.5 to 1.4) | 0.9 (0.5 to 1.7) | 0.7 (0.3 to 1.6) |
| Smoker/no silica exposure | 6874/61 199 | 0.00 | – | 14 | 1.8 (1.6 to 2.0) | 2.2 (1.9 to 2.5) | 1.1 (0.9 to 1.3) |
| Smoker/exposed to silica | 578/3670 | 0.08 | 26 | 20 | 2.5 (1.8 to 3.5) | 3.1 (2.2 to 4.4) | 1.4 (0.9 to 2.4) |
*Adjusted for county, age, index year, pack-years of smoking and alcohol consumption. Asbestos and silica were adjusted for each other.
†Additionally adjusted for sex.
RA, rheumatoid arthritis.