| Baltic | Danish | Norwegian | |||
---|---|---|---|---|---|---|
 | cases | controls | cases | controls | cases | Controls |
 | N = 441 | N = 1156 | N = 560 | N = 796 | N = 274 | N = 282 |
Sex distribution | Â | Â | Â | Â | Â | Â |
   % female | 50 | 51 | 48 | 52 | 48 | 41 |
Age at sampling | Â | Â | Â | Â | Â | Â |
   Median age (years, SD) | 44 [17] | 40 [12] | 49 [16] | 43 [11] | 39 [15] | 32 [7] |
Age of diagnosis | Â | Â | Â | Â | Â | Â |
   Median age (years, SD) | 38 [16] |  | 35 [11] |  | 38 [15] |  |
Disease extent, % | Â | Â | Â | Â | Â | Â |
   Left sided colitis | 76 |  | 80 |  | 69 |  |
   Extensive colitis | 24 |  | 20 |  | 31 |  |
Smoking habits, % | Â | Â | Â | Â | Â | Â |
   Current | 12 |  | 17 |  | 13 |  |
   previous | 28 |  | 36 |  | 31 |  |
   never | 60 |  | 47 |  | 56 |  |