Table 4.
Relative risk of rheumatoid arthritis among former smokers by years since quitting and age at quitting cigarette smoking in the Swedish Mammography Cohort, 2003 to 2010
| Person-years1 | Cases, number1 | Age-adjusted relative risk | 95% CI | Multivariable relative risk2 | 95% CI | |
|---|---|---|---|---|---|---|
| Never smokers | 137,162 | 79 | 1.00 (ref) | 1.00 (ref) | ||
| Years since quitting | ||||||
| 1-14 | 23,297 | 20 | 1.45 | 0.88, 2.38 | 1.50 | 0.68, 3.30 |
| ≥ 15 (median 24) | 35,613 | 39 | 1.85 | 1.25, 2.73 | 1.99 | 1.23, 3.20 |
| Age at quitting | ||||||
| ≤ 41 (median 32) | 31,164 | 31 | 1.68 | 1.09, 2.59 | 1.94 | 1.18, 3.18 |
| > 41 (median 50) | 27,747 | 28 | 1.70 | 1.11, 2.62 | 2.02 | 1.01, 4.07 |
1 Numbers do not add up to the totals because of missing values. 2Adjusted for age (continuous), menopausal status (pre- or postmenopausal), parity (0, 1, 2, or ≥ 3 children), alcohol use(none, former, or current), educational level (lower than high school, high school, or university), body mass index (quartiles), and pack-years of smoking (continuous among former smokers). Ref, reference group.