Table 1.
Baseline characteristics of inflammatory bowel disease patients who underwent testing for human anti-chimeric antibodies and infliximab concentrations
| Characteristic | N =155 |
|---|---|
| Females, n (%) | 86 (55%) |
| Median age at diagnosis of inflammatory bowel disease (IQR) | 25 (18–36) |
| Median age at time of initial test, years (IQR) | 39 (26–50) |
| Smoking status, n (%) | |
| Current | 82 (21%) |
| Former (> 1 month with no smoking) | 24 (15%) |
| Crohn’s disease | 121 (78%) |
| Ileal | 19 (16%) |
| Colonic only | 35 (29%) |
| Ileocolonic | 67 (55%) |
| Perianal disease | 29 (24%) |
| Surgical management before anti-TNF | 65 (54%) |
| Ulcerative colitis | 31 (20%) |
| Left-sided disease | 7 (23%) |
| Pan-colonic disease | 24 (77%) |
| Indeterminate colitis | 3 (2%) |
| Concomitant medication (at the time of initial test) | |
| Mesalamine | 11 (7%) |
| Corticosteroids (> 20 mg/day) | 16 (10%) |
| Azathioprine/6-merca ptopuri ne | 57 (37%) |
| Methotrexate | 12 (10%) |
| Induction dosing (0, 2, 6 weeks) | 127 (82%) |
| History of steroid pretreatment | 16 (10%) |
| Initial response to infliximab | |
| Complete response | 100 (65%) |
| Partial response | 45 (29%) |
| No response | 10 (6%) |
| Median time to initial testing after infliximab initiation, weeks (IQR) | 50 (22.7–120) |
| Median number of infusions (per patient) before test (IQR) | 8 (4–15) |
IQR, interquartile range; TNF, tumor necrosis factor.