From: Cigarette smoking and smoking cessation in relation to risk of rheumatoid arthritis in women
 |  |  | Intensity | |||
---|---|---|---|---|---|---|
 | Cases, number | Never smokers | Cases, number | 1 to 10 Cigarettes/day | Cases, number | > 10 Cigarettes/day |
Duration | Â | Â | Â | Â | Â | Â |
Never smokers | 79 | 1.00 (ref) | Â | - | Â | - |
1 to 30 years (median 17) | Â | - | 38 | 1.96 (1.31, 2.93) | 11 | 1.12 (0.59, 2.14) |
> 30 years (median 38) | Â | - | 51 | 2.54 (1.76, 3.69) | 25 | 1.56 (0.98, 2.50) |