Arthritis conditions associated with coal and silica exposure, adjusted for ergonomic exposures, smoking and age (2019 sample only)
| Multivariate logistic models | Any arthritis | Non-RA arthritis | RA (sensitive) | RA (specific) |
| (Model n=2008) | (Model n=1806) | (Model n=1039) | (Model n=925) | |
| Prevalence of arthritis by type (95% CI) | 58% (56% to 60%) | 48% (46% to 50%) | 10% (9% to 11%) | 4% (3% to 5%) |
| Model 1: coal and/or silica exposure | ORs (95% CIs) | |||
| No exposure to coal mining or other occupational silica | Referent | Referent | Referent | Referent |
| Coal mining exposure | 1.8 (1.4 to 2.3) | 1.7 (1.27 to 2.2) | 2.3 (1.52 to 3.6) | 2.3 (1.18 to 4.5) |
| Silica exposure from non-coal occupations only | 1.3 (1.1 to 1.7) | 1.2 (0.97 to 1.6) | 1.8 (1.20 to 2.7) | 2.7 (1.51 to 5.0) |
| Ergonomic hazard score (referent category=0) | ||||
| one point | 1.5 (1.2 to 2.0) | 1.5 (1.09 to 1.9) | 2.4 (1.30 to 4.2) | 1.8 (0.76 to 4.4) |
| 2–3 points | 2.0 (1.5 to 2.5) | 1.8 (1.43 to 2.4) | 3.2 (1.91 to 5.4) | 2.4 (1.12 to 5.2) |
| 4–5 points | 2.6 (2.0 to 3.5) | 2.3 (1.68 to 3.1) | 5.4 (3.14 to 9.5) | 4.3 (1.96 to 9.6) |
| Model 2: intensity of exposure | ||||
| No exposure to coal mining or other occupational silica | Referent | Referent | Referent | Referent |
| High silica coal mining exposure | 1.9 (1.4 to 2.6) | 1.8 (1.27 to 2.4) | 2.6 (1.60 to 4.4) | 2.6 (1.21 to 5.5) |
| All other coal mining exposure | 1.6 (1.1 to 2.3) | 1.5 (1.04 to 2.3) | 1.9 (1.05 to 3.6) | 1.9 (0.76 to 4.9) |
| Silica exposure from non-coal occupations only | 1.3 (1.1 to 1.7) | 1.2 (0.97 to 1.6) | 1.8 (1.20 to 2.7) | 2.7 (1.51 to 5.0) |
| Ergonomic hazard score (referent category=0) | ||||
| 1 point | 1.5 (1.2 to 2.0) | 1.4 (1.09 to 1.9) | 2.4 (1.31 to 4.3) | 1.8 (0.77 to 4.5) |
| 2–3 points | 2.0 (1.5 to 2.5) | 1.8 (1.42 to 2.4) | 3.2 (1.90 to 5.4) | 2.4 (1.11 to 5.2) |
| 4–5 points | 2.6 (2.0 to 3.5) | 2.3 (1.68 to 3.1) | 5.4 (3.12 to 9.4) | 4.3 (1.94 to 9.5) |
| Model 3: underground coal mining exposure | ||||
| No exposure to coal mining or other occupational silica | Referent | Referent. | Referent | Referent |
| No underground work | 1.5 (1.0 to 2.2) | 1.5 (1.02 to 2.2) | 1.5 (0.78 to 2.9) | 1.5 (0.58 to 4.1) |
| 1–17 years | 1.6 (1.1 to 2.4) | 1.5 (0.96 to 2.2) | 2.4 (1.27 to 4.4) | 2.7 (1.08 to 6.5) |
| ≥18 years | 2.5 (1.6 to 3.9) | 2.3 (1.43 to 3.6) | 3.8 (1.99 to 7.2) | 3.1 (1.19 to 8.3) |
| Silica exposure from non-coal occupations only | 1.3 (1.1 to 1.7) | 1.2 (0.97 to 1.6) | 1.8 (1.19 to 2.7) | 2.7 (1.51 to 5.0) |
| Ergonomic hazard score (referent category=0 points) | ||||
| 1 point | 1.5 (1.2 to 2.0) | 1.4 (1.08 to 1.9) | 2.4 (1.30 to 4.3) | 1.9 (0.77 to 4.5) |
| 2–3 points | 2.0 (1.5 to 2.5) | 1.8 (1.42 to 2.4) | 3.1 (1.85 to 5.2) | 2.4 (1.10 to 5.1) |
| 4–5 points | 2.6 (1.9 to 3.5) | 2.3 (1.67 to 3.1) | 5.5 (3.15 to 9.5) | 4.4 (1.97 to 9.6) |
All models shown in table control for the other variables shown in model plus age and smoking (never, former, current/recent). Sensitive RA case definition is based on report of doctor’s diagnosis of RA, plus treatment with glucocorticoids. Specific RA case definition based on report of doctor’s diagnosis of RA, plus treatment with disease modifying anti-rheumatic drugs. Models of RA exclude respondents who report arthritis not meeting the given definition, including general arthritis (n=759) but also RA not meeting the sensitive definition in that model (n=210) or RA not meeting the more specific definition (n=114).
RA, rheumatoid arthritis.