Table 4.
Characteristics of the patients with and without an infection during thiopurine treatment
| Characteristics | Infection during thiopurine treatment | P‐value | |
|---|---|---|---|
| Yes (n = 59) | No (n = 636) | ||
| Male sex, n (%) | 21 (36) | 289 (45) | .15 |
| Age,y, median (IQR) | 42 (33‐60) | 40 (26‐53) | .11 |
| BMI, mean (SD) | 24.9 (6.1) | 24.7 (4.7) | .82 |
| Current smoker, n (%) | 18 (31) | 142 (22) | .16 |
| Drug, AZA, n (%) | 42 (71) | 406 (64) | .26 |
| Thiopurine dose in mg/kg, median (IQR)c | 1.08 (1.02‐1.16) | 1.10 (1.02‐1.19) | .50 |
| TPMT activity, mg/mmol Hb.h, mean (SD) | 96.2 (19.6) | 94.4 (18.9) | .47 |
| Disease, CD, n (%)a | 38 (64) | 385 (61) | .63 |
| Wk 0 WBC count, 109/L, mean (SD) | 9.9 (3.5) | 10.5 (3.6) | .21 |
| Wk 1 decrease WBC count, 109/L, mean (SD)c | 0.4 (3.0) | 0.9 (2.8) | .29 |
| Leucopenia | 5 (9)c | 37 (6) | .41 |
| Concomitant drugs, n (%) | |||
| 5‐Aminosalicylic acid | 28 (48) | 317 (50) | .47 |
| Systemic steroids | 33 (56) | 632 (58) | .79 |
| Biologics | 12 (20) | 63 (10) | .01 |
| ACE‐inhibitor | 2 (4) | 20 (3) | .61 |
| Co‐morbidity, n (%)b | |||
| Diabetes mellitus | 1 (2) | 24 (4) | .41 |
| Rheumatic disease | 8 (16) | 61 (11) | .32 |
| Asthma/COPD | 5 (10) | 33 (6) | .28 |
| Disease severity | |||
| CD, HBI, mean (SD)e | 3.7 (2.8) | 3.6 (3.1) | .80 |
| UC, partial Mayo, mean (SD)f | 3.9 (1.7) | 3.8 (1.7) | .82 |
Leucopenia was defined as a WBC count of <3.0 × 109/L. Only infections grade 2 or higher according to the Common Terminology Criteria for Adverse Events were included.
AZA, azathioprine; BMI, body mass index; CD, Crohn's disease; HBI; Harvey‐Bradshaw Index; TPMT, thiopurine S‐methyltransferase; UC, ulcerative colitis; WBC, white blood cell.
AZA dose in mg/kg was divided by 2.08 to compare with MP dosage.
Seven patients were diagnosed with indeterminate colitis.
Known for 492 patients.
Known for 602 patients.
Known for 325 patients with CD.
Known for 225 patients with UC.
As follows from Table 3, 45 patients experienced leucopenia, however in 3 patients with leucopenia during thiopurine treatment who also had an infection, the infection was not considered to be related to leucopenia, either because leucopenia was already resolved for more than 2 weeks (2 patients), or the infection was already known before the leucopenia occurred (1 patient). For the analysis, these cases were counted as an infection without leucopenia.