Table 3.
Adjusted odds ratios for developing rheumatoid arthritis according to smoking and rheumatoid factor status in men
| Number of observations entering the multivariable model | |||
| Parameter | RA cases | Controls | Odds ratio* (95% CI) |
| All RA | |||
| Current smoking | 306 | 418 | 1.2 (0.7–2.0) |
| Past smoking | 234 | 306 | 2.0 (1.2–3.2) |
| RF-positive RA | |||
| Current smoking | 181 | 418 | 1.5 (0.8–2.6) |
| Past smoking | 140 | 306 | 2.3 (1.3–3.9) |
| RF-negative RA | |||
| Current smoking | 125 | 418 | 0.8 (0.3–1.8) |
| Past smoking | 94 | 306 | 1.5 (0.7–3.0) |
*Odds ratios are expressed as the expected probability of having rheumatoid arthritis (RA) as compared with those who did not smoke. The confounders adjusted for in the multivariable logistic regression models included age, body mass index, number of years of education, Health Assessment Questionnaire disability index, general health assessment, and pain. CI, confidence interval.