Relative risk of RA by history of periodontal surgery among women in the Nurses’ Health Study, 1992–2004, stratified by ever (n = 45,376) and never (n = 35,745) smokers and by heavy (n = 29,514) and not heavy (n = 50,410) smokers.
| Factor | Smoking | Cases, n | Person-years | Multivariate RR (95% CI)* | p |
|---|---|---|---|---|---|
| Periodontal surgery | |||||
| No | Ever | 157 | 451,123 | 1.0 (ref) | |
| Yes | 22 | 44,890 | 1.44 (0.92, 2.27) | 0.11 | |
| No | Never | 106 | 375,690 | 1.0 (ref) | |
| Yes | 6 | 23,747 | 0.91 (0.40, 2.08) | 0.82 | |
| No | ≤ 10 pack-years | 136 | 527,434 | 1.0 (ref) | |
| Yes | 9 | 36,368 | 0.99 (0.50, 1.94) | 0.97 | |
| No | > 10 pack-years | 117 | 288,171 | 1.0 (ref) | |
| Yes | 18 | 31,244 | 1.48 (0.89, 2.45) | 0.13 | |
↵* Adjusted for number of natural teeth, alcohol intake, cigarettes smoked per day (among smokers), body mass index, father’s occupation, age at menarche, postmenopausal status and hormone use, duration of breastfeeding, and regularity of menses.