Fig. 5.

Association between IgA subclasses and smoking in seropositive RA patients

IgA subclass levels in ever- versus never-smoking seropositive RA patients in (A) IMPROVED and (B) EAC, analysed using Mann–Whitney U tests. Red bars: median and interquartile range. *P < 0.05, **P < 0.01, ***P < 0.001, ^#not significant after correction for multiple testing. In RF IgA subclass analyses, only patients positive for both RF IgA1 and RF IgA2 are included. For anti-CCP2 IgA1 analysis, only anti-CCP2 IgA1 positive patients are included. Of note, RF and anti-CCP2 IgA subclass levels were not titrated. Colour version available online.