Characteristics of the patient and control groups
| Group | PSC-IBD (n = 78) | PSC-IBD controls (n = 390) | Pure PSC (n = 12) | Pure PSC controls (n = 60) | UC (n = 294) | UC controls (n = 1016) |
|---|---|---|---|---|---|---|
| PSC, primary sclerosing cholangitis; IBD, inflammatory bowel disease; UC, ulcerative colitis. | ||||||
| *Never smoking in PSC-IBD versus PSC-IBD controls, p = 0.004, odds ratio (OR) = 2.2 (confidence interval (CI) 1.3–3.8). | ||||||
| †Appendicectomy data not available for one PSC-IBD, 43 PSC-IBD controls, six pure PSC controls, and 117 UC controls. | ||||||
| ‡Appendicectomy in PSC-IBD versus UC, p<0.0001, OR = 4.7 (CI 2.4–9.5). | ||||||
| §Appendicectomy in pure PSC versus UC, p = 0.008, OR = 7.2 (CI 2.0–26). | ||||||
| ¶Appendicectomy in UC versus UC controls, p = 0.0001, OR = 0.23 (CI 0.14–0.37). | ||||||
| Age (y) (mean (SEM)) | 49.8 (1.5) | 52.0 (0.5) | 55.8 (4.3) | 57.3 (0.5) | 32.7 (0.86) | 33.6 (0.38) |
| Sex | ||||||
| Female | 37 | 185 | 5 | 25 | 142 | 465 |
| Male | 41 | 205 | 7 | 35 | 152 | 551 |
| Smoking | ||||||
| Ever smoker | 23 | 188 | 7 | 29 | 136 | 482 |
| Never smoker | 55* | 202 | 5 | 31 | 158 | 534 |
| Appendicectomy† | ||||||
| No | 58 | 268 | 8 | 40 | 275 | 688 |
| Yes | 19‡ | 79 | 4§ | 14 | 19¶ | 211 |
| Age at appendicectomy | ||||||
| None | 58 | 268 | 9 | 40 | 275 | 688 |
| ⩽20 y | 11 | 50 | 1 | 9 | 8 | 136 |
| >20 y | 8 | 29 | 2 | 5 | 11 | 68 |