First inhibitor titer (BU/mL) value by EDs^a for first LTI and HTI development^b-e.^aBefore inhibitor development or inhibitor progression. ^bImmune tolerance induction regimen is excluded from this analysis. ^cTwo patients have no data post LTI/HTI development. ^dCategorization of titer level requires a positive inhibitor test result followed by a second positive test result 2 to 4 weeks after the original sample was drawn. This analysis is based on the first of the 2 inhibitor readings. The categorization of the patient with LTIs with a value of ∼11 BU at 5 EDs was based on failing to achieve a second repeat inhibitor test above 5 BU/mL needed to confirm HTI classification. ^eSeven of the patients with HTIs (50%) had previously developed an LTI.