Comparison of admission rates before and after appendicectomy, stratified by time since onset of ulcerative colitis (UC). The analysis is based only on subjects from the index cohort
| Time since UC onset (y) | Before appendicectomy | After appendicectomy | After/before appendicectomy | |||||
|---|---|---|---|---|---|---|---|---|
| No of UC admissions | Follow up (person years) | Incidence rate | No of UC admissions | Follow up (person years) | Incidence rate | Rate ratios | Confidence intervals | |
| NA, not applicable. | ||||||||
| 0–2 | 83 | 177 | 0.47 | 7 | 24 | 0.3 | 0.62 | 0.24–1.34 |
| 2–4 | 19 | 145 | 0.13 | 8 | 54 | 0.15 | 1.13 | 0.43–2.70 |
| 4–6 | 33 | 216 | 0.15 | 31 | 160 | 0.19 | 1.26 | 0.75–2.14 |
| 6–8 | 22 | 203 | 0.11 | 34 | 273 | 0.12 | 1.14 | 0.65–2.06 |
| 8–10 | 10 | 125 | 0.08 | 17 | 262 | 0.06 | 0.82 | 0.35–2.00 |
| ⩾10 | 4 | 87 | 0.05 | 20 | 450 | 0.04 | 0.97 | 0.32–3.90 |
| All person time | 171 | 953 | NA | 117 | 1221 | NA | 1.02 | 0.78–1.35 |