Correlation between ANA titer and clinical response to IFX. (a) Correlations between ANAs before starting therapy with IFX and clinical response to IFX. EULAR response (upper) and DAS28 after IFX (lower) were significantly different by ANA titer before IFX (P = 0.001 and 0.002, respectively, by Jonckheere-Terpstra trend test). The efficacy of IFX became worse as the ANA titer increased before starting IFX. (b) These clinical responses to IFX were analyzed with ANAs after starting IFX. The differences became more marked (P < 0.001 in both EULAR response (upper) and DAS 28 after IFX (lower), by the Jonckheere-Terpstra trend test). *Analyzed with the Jonckheere-Terpstra trend test. †Mean changes of DAS28 score before and after IFX.