Table 2.

Agreement between different assays regarding levels of IFX: (A) analytical approach and (B) clinical approach.

	Agreement
	Accuracy	KAPPA [95% CI]
(A) IFX (>0.1 µg/ml in-house and Theradiag; 0.5 µg/ml Immundiagnostik)
In-house ELISA/ Theradiag ELISA	81%	0.509 [0.295–0.722]
In-house ELISA/ Immundiagnostik ELISA	87%	0.697 [0.526–0.868]
Immundiagnostik ELISA / Theradiag ELISA	88%	0.726 [0.559–0.893]
(B) IFX (>1 µg/ml)
In-house ELISA/ Theradiag ELISA	92%	0.840 [0.716–0.963]
In-house ELISA/ Immundiagnostik ELISA	96%	0.922 [0.836–1.000]
Immundiagnostik ELISA / Theradiag ELISA	92%	0.835 [0.709–0.960]

CI, confidence interval; ELISA, enzyme-linked immunosorbent assay; IFX, infliximab.