OR with 95% CI of developing rheumatoid arthritis (RA) for subjects exposed to passive smoking compared with those who have never been exposed
| Exposure to passive smoking | ACPA-positive RA | ACPA-negative RA | ||
| ca/co | OR (95% CI)* | ca/co | OR (95% CI)* | |
| Never | 205/888 | 1.0 (reference) | 106/888 | 1.0 (reference) |
| Ever | 180/876 | 1.0 (0.8 to 1.2) | 98/876 | 0.9 (0.7 to 1.2) |
| Within 10 years prior to index | 45/170 | 1.1 (0.8 to 1.7) | 15/170 | 0.7 (0.4 to 1.3) |
| Before 10 years prior to index | 135/706 | 0.9 (0.7 to 1.2) | 83/706 | 1.0 (0.7 to 1.3) |
All subjects were never-smokers.
*Adjusted for age, gender, residential area and ancestry.
ACPA, anti-cyclic citrullinated peptide antibodies; ca/co, number of exposed cases and controls.