Table 1.
Cohort demographics n (%)
| Variables | Total (n = 351) | Discontinued due to adverse event (n = 110) | Continued therapy (n = 241) | P value |
| Gender | 0.36 | |||
| Female | 185 (52.7) | 62 (56.3) | 123 (51.1) | |
| Male | 166 (47.3) | 48 (43.6) | 118 (48.9) | |
| Age at diagnosis (A) (yr) | 0.05 | |||
| < 17 | 56 (16.0) | 13 (11.8) | 43 (17.8) | |
| 17-40 | 233 (66.4) | 70 (63.3) | 163 (67.6) | |
| > 40 | 62 (17.7) | 27 (24.5) | 35 (14.5) | |
| Age at thiopurine (yr) | 0.007 | |||
| < 17 | 21 (6.5) | 5 (4.5) | 16 (6.6) | |
| 17-40 | 195 (60.0) | 44 (40.0) | 151 (62.7) | |
| > 40 | 109 (33.5) | 43 (39.1) | 66 (27.4) | |
| L4 (upper gastrointestinal disease) | 0.52 | |||
| Yes | 27 (7.7) | 10 (9.1) | 17 (7.1) | |
| No | 324 (92.3) | 100 (90.1) | 224 (92.9) | |
| Behaviour (B) (%) | 0.91 | |||
| B1 (inflammatory) | 183 (56.0) | 55 (50.0) | 128 (53.1) | |
| B2 (fibrostenotic) | 62 (19.0) | 20 (18.2) | 42 (17.4) | |
| B3 (penetrating) | 82 (25.1) | 26 (23.6) | 56 (23.2) | |
| Perianal disease before thiopurine | 0.69 | |||
| Yes | 82 (23.4) | 24 (21.8) | 58 (24.1) | |
| No | 269 (76.6) | 86 (78.2) | 183 (75.9) | |
| Corticosteroid at diagnosis | 0.35 | |||
| Yes | 142 (52.8) | 39 (35.5) | 103 (42.7) | |
| No | 127 (47.2) | 42 (38.2) | 85 (35.3) | |
| Pre-thiopurine intestinal resection | 0.81 | |||
| Yes | 140 (39.9) | 45 (40.9) | 95 (39.4) | |
| No | 211 (60.1) | 65 (59.1) | 146 (60.6) | |
| Disease duration before thiopurines (yr) | 0.22 | |||
| < 1 | 100 (30.8) | 22 (20.0) | 78 (32.4) | |
| 1-5 | 81 (24.9) | 22 (20.0) | 59 (24.5) | |
| 5-10 | 63 (19.4) | 23 (20.9) | 40 (16.6) | |
| > 10 | 81 (24.9) | 25 (22.7) | 56 (23.2) | |
| 5-ASA exposure before thiopurine | 66 (24.8) | 18 (16.4) | 48 (19.9) | 0.47 |
| Anti-TNFα exposure1 | < 0.0001 | |||
| Thiopurine monotherapy | 234 (66.7) | 97 (88.2) | 137 (56.9) | |
| Non-con. Comb. therapy | 79 (22.5) | 5 (4.5) | 74 (30.7) | |
| Con. Comb therapy | 38 (10.8) | 8 (7.3) | 30 (12.4) | |
| Smoking history | 0.12 | |||
| Never | 180 (51.3) | 48 (43.6) | 132 (54.8) | |
| History of smoking | 126 (35.9) | 49 (44.5) | 77 (32.0) | |
| Unknown | 45 (12.8) | 13 (11.8) | 32 (13.2) |
1
Thiopurine monotherapy, defined as patients naive to anti-TNF therapy or suffering an adverse event that led to discontinuation of the thiopurine prior to exposure to anti-TNF therapy; non-concomitant onset combination therapy defined as anti-TNF therapy started more than 3 mo after thiopurine onset; concomitant onset combination therapy defined as concomitant prescription of thiopurine and anti-TNF within 3 mo. Clinical characteristics of the 351 CD patients treated with a thiopurine stratified by an adverse event requiring withdrawal of thiopurines. Anti-TNF: Anti-tumour necrosis factor; ASA: Aminosalicylic acid; CD: Crohn's disease.