Significance of low level infliximab in the absence of anti-infliximab antibodies

Figure 1 Flow chart of the patients included in the two parts of this study. The analytical part (dashed lines) comprised a comparison of two different assays and of two different serum dilutions; the clinical part (solid lines) followed up, in a case-control study, double negative patients versus patients with adequate infliximab levels for subsequent antibodies to infliximab formation and clinical outcome. DN: Double negative; LOR: Loss of response; AL: Anti-lambda; DA: Double-antigen; IFX: Infliximab; ATI: Antibodies to infliximab.