Appendicectomy before ulcerative colitis showing data in five year age groups at time of appendicectomy, and showing data for people who underwent appendicectomy with or without a record of appendicitis: observed (Obs) and expected (Exp) numbers of people in each subgroup, and the ratios of observed to expected (O/E) with their 95% confidence intervals (CI)
| Operation | Age (y) | Obs | Exp | O/E | 95% CI |
|---|---|---|---|---|---|
| All appendicectomy | <5 | 0 | 0.5 | 0 | 0 to 7.94 |
| 5–9 | 4 | 5.8 | 0.69 | 0.18 to 1.79 | |
| 10–14 | 5 | 17.3 | 0.29 | 0.09 to 0.68 | |
| 15–19 | 13 | 22.1 | 0.59 | 0.31 to 1.01 | |
| 20–24 | 14 | 16.7 | 0.84 | 0.46 to 1.41 | |
| 25–29 | 15 | 12.9 | 1.17 | 0.65 to 1.93 | |
| 30–34 | 13 | 10.3 | 1.26 | 0.67 to 2.17 | |
| ≥35 | 55 | 40.8 | 1.35 | 1.02 to 1.76 | |
| Appendicectomy with appendicitis | <20 | 15 | 35.3 | 0.43 | 0.24 to 0.70 |
| ≥20 | 67 | 58.2 | 1.15 | 0.89 to 1.46 | |
| Appendicectomy without appendicitis | <20 | 7 | 10.4 | 0.67 | 0.27 to 1.39 |
| ≥20 | 30 | 22.4 | 1.34 | 0.90 to 1.92 |