Association between appendectomy and Crohn’s disease or ulcerative colitis, Quebec Birth Cohort on Immunity and Health, Canada, 1970–2014 (N=400 513)
| Cases (n) | Follow-up (person-years) | Crude HR (95% CI) | Adjusted HR* (95% CI) | |
| Crohn’s disease | ||||
| Appendectomy | ||||
| No | 2433 | 12 370 413 | 1 (reference) | 1 (reference) |
| Yes | 112 | 285 154 | 1.97 (1.63 to 2.39) | 2.02 (1.66 to 2.44) |
| Age at appendectomy (years)† | ||||
| 8–17 | 16 | 105 013 | 1 (reference) | 1 (reference) |
| 18–29 | 89 | 142 418 | 2.90 (1.70 to 4.94) | 2.81 (1.65 to 4.78) |
| ≥30 | 7 | 37 723 | 0.44 (0.18 to 1.07) | 0.42 (0.17 to 1.02) |
| Elapsed time post appendectomy (years)† | ||||
| 0–2 | 59 | 33 576 | 4.24 (2.56 to 6.99) | 4.20 (2.54 to 6.93) |
| 3–5 | 21 | 49 883 | 1 (reference) | 1 (reference) |
| 6–11 | 21 | 60 270 | 0.57 (0.31 to 1.05) | 0.58 (0.31 to 1.06) |
| ≥12 | 11 | 253 941 | 0.31 (0.15 to 0.64) | 0.32 (0.15 to 0.67) |
| Ulcerative colitis | ||||
| Appendectomy | ||||
| No | 1123 | 12 370 413 | 1 (reference) | 1 (reference) |
| Yes | 11 | 285 154 | 0.39 (0.21 to 0.71) | 0.39 (0.22 to 0.71) |
| Age at appendectomy (for 1 year increase)† | 11 | 285 154 | 1.06 (0.97 to 1.14) | 1.06 (0.97 to 1.15) |
| Elapsed time post appendectomy (years) † | ||||
| 0–4 | 6 | 65 462 | 1 (reference) | 1 (reference) |
| ≥5 | 5 | 219 692 | 0.21 (0.06 to 0.72) | 0.21 (0.06 to 0.72) |
Compilation based on data from the Government of Québec, Institut de la statistique du Québec, 2017. Institut de la statistique du Québec is not responsible for compilations or interpretation of results.
*Adjusted for gestational age and sex.
†Among those who had an appendectomy.