Rate ratios of inflammatory bowel diseases according to antibiotic use among Danish children born 1995–2003 followed from birth until 1 January 2005
| Inflammatory bowel diseases | Crohn's disease | Ulcerative colitis | |||||||
| Number of cases | RR* | 95% CI | Number of cases | RR* | 95% CI | Number of cases | RR* | 95% CI | |
| Antibiotic use | |||||||||
| No courses | 33 | 1 | Reference | 11 | 1 | Reference | 22 | 1 | Reference |
| At least 1 course | 84 | 1.84 | (1.08 to 3.15) | 39 | 3.41 | (1.45 to 8.02) | 45 | 1.21 | (0.61 to 2.38) |
| Use in last 3 months | 26 | 2.39 | (1.36 to 4.19) | 14 | 4.43 | (1.88 to 10.44) | 12 | 1.49 | (0.69 to 3.19) |
| Use >3 months previously | 58 | 1.42 | (0.79 to 2.53) | 25 | 2.27 | (0.88 to 5.84) | 33 | 1.04 | (0.50 to 2.16) |
| Number of courses | |||||||||
| 1–2 | 32 | 1.63 | (0.92 to 2.91) | 14 | 2.94 | (1.18 to 7.31) | 18 | 1.11 | (0.54 to 2.32) |
| 3–4 | 21 | 2.07 | (1.03 to 4.18) | 11 | 5.12 | (1.69 to 15.53) | 10 | 1.12 | (0.45 to 2.80) |
| 5–6 | 15 | 2.76 | (1.27 to 5.97) | 6 | 5.30 | (1.49 to 18.87) | 9 | 1.86 | (0.71 to 4.87) |
| 7+ | 16 | 2.93 | (1.34 to 6.40) | 8 | 7.32 | (2.14 to 24.99) | 8 | 1.59 | (0.57 to 4.39) |
| Increase in RR per course | 1.12 | (1.04 to 1.21) | 1.18 | (1.06 to 1.32) | 1.08 | (0.97 to 1.19) | |||
↵* Adjusted for age and calendar period.