Infliximab and antibodies to infliximab levels
| Total number of patients | 85 |
| Age, mean, years (SD) | 39.13 (±14.25) |
| Sex, male, n (%) | 54 (64) |
| Weight, mean, kg (SD) | 76.13 (15.54) |
| Previous/current smoker, n (%) | 25 (29) |
| Family history of IBD, n (%) | 6 (7) |
| Crohn’s disease, n (%) | 62 (73) |
| Ulcerative colitis, n (%) | 23 (27) |
| Previous surgical treatment, n (%) | 26 (31) |
| Stricturoplasty | 7 (8) |
| Subtotal colectomy | 5 (6) |
| Ileocaecal resection | 8 (9) |
| Fistula resection | 2 (2) |
| Small bowel resection | 3 (4) |
| Right hemicolectomy | 6 (7) |
| Abdominoperineal resection | 1 (1) |
| Emergency laparotomy | 2 (2) |
| Previous immunosuppressive drugs, n (%) | |
| Azathioprine | 79 (93) |
| Methotrexate | 18 (21) |
| Ciclosporin | 3 (4) |
| Adalimumab | 6 (7) |
| 6-mercaptapurine | 14 (16) |
| Tacrolimus | 1 (1) |
| Combination therapy at the time of drug level | 46 (54) |
| Number of drug levels done per patient, n | |
| One | 57 |
| Two | 22 |
| Three | 3 |
| Four | 3 |
| Mean CRP at baseline, mg/L (SD) | |
| Active (n = 69) | 14.03 (±21.39) |
| Remission (n = 53) | 4.73 (±5.86) |
| p value | 0.001 |
| Mean haemoglobin at baseline, g/L (SD) | |
| Active (n = 69) | 134.31 (±14.32) |
| Remission (n = 53) | 140.56 (±13.24) |
| p value | 0.007 |
| Mean calprotectin at baseline, pg/g (SD) | |
| Active (n = 69) | 270.56 (±341.43) |
| Remission (n = 53) | 58.8 (±123.70) |
| p value | 0.013 |
CRP = C-reactive protein; IBD = irritable bowel disease; SD = standard deviation.