Table 3.
Trough infliximab concentration (mg/L) during infliximab initiation for ATIpos and ATIneg patients with RA and SpAa
| RA (n = 17) | SpA (n = 91) | |||||
|---|---|---|---|---|---|---|
| Time after infliximab initiation | ATIpos (n = 7) | ATIneg (n = 10) | P value | ATIpos (n = 14) | ATIneg (n = 77) | P value |
| Week 2 | 7.7 (2.8 to 16.9) | 27.2 (7.1 to 41.9) | 0.002 | 25.0 (4.0 to 40.7) | 35.8 (14.3 to 57.2) | 0.003 |
| Week 6 | 0.3 (0 to 6.2) | 15.4 (2.7 to 35.0) | 0.001 | 11.9 (0 to 24.2) | 29.5 (3.4 to 69.0) | < 0.001 |
| Weeks 12 and 14 | 0 (0 to 0.03) | 5.4 (0 to 21.9) | 0.01 | 1.6 (0 to 13.5) | 15.8 (0.7 to 47.3) | < 0.001 |
aATI: antibodies toward infliximab; ATIpos: ATI detected at least once during follow-up; ATIneg: ATI not detected; RA: rheumatoid arthritis; SpA: spondyloarthritis. Results are given as medians (ranges).