Methotrexate Reduced TNF Bioactivity in Rheumatoid Arthritis Patients Treated with Infliximab

Figure 2

TNF bioactivity, DAS28, and IFX trough concentration at W22 in function of presence of IFX with or without ATI at W22 and IFX trough concentration and ATI at W22 and clinical response at W22. High TNF bioactivity was observed in the group “Low IFX trough concentration with ATI,” but not in the groups “Low IFX trough concentration without ATI” and “High IFX trough concentration without ATI” ((a) Kruskal-Wallis rank sum test; ). DAS28 was higher in the “Low IFX trough concentration with ATI” group compared to the two others ((b) Kruskal-Wallis rank sum test; ). IFX trough concentration at W22 was heterogeneous in the three groups ((c) Kruskal-Wallis rank sum test; ) with highest IFX trough concentration in the group “High IFX trough concentration without ATI.” Furthermore, IFX trough concentration was higher in the group “Low IFX trough concentration without ATI” than in the group “Low IFX trough concentration with ATI” ((c) ). IFX trough concentration was higher in the group “High IFX trough concentration without ATI” than in the group “Low IFX trough concentration without ATI” ((c) ). A trend for high IFX trough concentration and good EULAR response was observed at W22 ((d) Kruskal-Wallis rank sum test ). Oppositely, ATI concentration was not detectable in good response and high in Null response at W22 ((e) Kruskal-Wallis rank sum test ). At W22, a trend between TNF bioactivity and EULAR response (f). TNF bioactivity was not detectable in good response and high in Null response at W22 (Kruskal-Wallis rank sum test; NS). The box plots show the median values and the first and third quartiles at each time. The T bars represent the rest of the data with a maximum of 1.5 times the interquartile range. Circles represent values lower or higher than 1.5 times the interquartile range. TNF: tumor necrosis factor; ATI: antibodies towards IFX; W: week; Low ITL: ITL lower than 2 μg/mL; High IFX trough concentration: infliximab trough concentration higher than 2 μg/mL; presence or absence of ATI was determined with a cut-off at 20 ng/mL.

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