Correlation between titers of FVIII-binding antibodies and FVIII inhibitor titers. (A) IgG1, (B) IgG2, (C) IgG3, (D) IgG4, (E) IgA, and (F) IgM. Spearman correlation coefficients with 95% CIs are given above the panels. Statistically significant correlations are marked with an asterisk (P < .05). ND, not detectable.