Many clinical studies in paediatric inflammatory bowel diseases (IBD) use infliximab trough level (IFX-TL) and detection of antibody against infliximab (ATI). Hence, comparison of commercially available assays is needed in paediatric samples to assess their reliability and their comparability.

We measured IFX-TL and ATI-TL in sera samples of 53 IBD children using three ELISA kits: Lisa-Tracker® Duo Infliximab (Theradiag®), Ridascreen® IFX monitoring (R-Biopharm®) and Promonitor® IFX (Grifols®).

Regarding IFX-TL, median values were comparable (p > 0.05), a good statistical correlation has been observed (0.73 ≤ R² ≤ 0.85) between tested assays and the Bland-Altman analysis found an excellent agreement with a bias estimated between −0.56 and 0.12 and few values outside the 95% limits of agreement. However, qualitative comparison with therapeutic interval classifications showed some discrepancies (30.2%), mainly due to values near thresholds and more often than not with Theradiag® (22.6%). For ATI, because of non-standardized units, the qualitative comparison found a sensibly good agreement (98.1%).

These data show a good agreement of IFX-TL and ATI measurement between three marketed ELISA assays with a small bias obtained. Variations in some results can lead to divergent therapeutic interval classifications and prompt us to be cautious in the interpretation of values near therapeutic thresholds.

许多儿科炎症性肠病 (IBD) 的临床研究使用英夫利昔单抗谷浓度 (IFX-TL) 和抗英夫利昔单抗抗体 (ATI) 检测。因此，需要在儿科样本中比较市售的检测方法，以评估其可靠性和可比性。

我们使用三种 ELISA 试剂盒测量了 53 名 IBD 儿童的血清样本中的 IFX-TL 和 ATI-TL：Lisa-Tracker® Duo Infliximab (Theradiag®)、Ridascreen® IFX 监测 (R-Biopharm®) 和 Promonitor® IFX (Grifols®) .

关于 IFX-TL，中值具有可比性（p > 0.05）， 在测试分析之间观察到良好的统计相关性（0.73 ≤ R ² ≤ 0.85），并且 Bland-Altman 分析发现极好的一致性，偏差估计在 -0.56 之间和 0.12 以及超出 95% 一致性限制的少数值。然而，与治疗间隔分类的定性比较显示出一些差异 (30.2%)，主要是由于接近阈值的值，并且通常与 Theradiag® (22.6%) 不同。对于 ATI，由于非标准化单位，定性比较发现了非常好的一致性 (98.1%)。

这些数据显示了三种市售的 ELISA 测定之间 IFX-TL 和 ATI 测量的良好一致性，并且获得了很小的偏差。某些结果的变化可能导致治疗间隔分类不同，并提示我们在解释接近治疗阈值的值时要谨慎。