Hemolytic adverse effects of intravenous immunoglobulin: modeling predicts risk reduction with anti-A/B immunoaffinity chromatography and to a lesser extent with anti-A donor screening.

BACKGROUND: The risk of hemolytic events (HEs) with intravenous immunoglobulin (IVIG) therapy appears to be linked to isoagglutinins (anti-A and anti-B) in the product. Patient risk factors include high IVIG dose, blood group, and underlying inflammatory state. STUDY DESIGN AND METHODS: Using published anti-A and anti-B titers for IVIG products and HE rates calculated from HEs spontaneously reported to EudraVigilance, regression models were developed to infer the relationship between HE risk and IVIG isoagglutinin levels for each blood group. Applying estimated model coefficients to isoagglutinin levels associated with an IVIG (Privigen; CSL Behring, King of Prussia, PA), manufactured with and without isoagglutinin reduction steps, predicted HE risk values were generated for each product: 1) without any isoagglutinin reduction, 2) anti-A donor screening, and 3) anti-A/anti-B specific immunoaffinity chromatography (IAC; Ig IsoLo). RESULTS: Predicted HE risk was highest for blood group AB, followed by A and B; it was low for O. Projected population shares of HEs by blood group were similar to reported real-world data. Compared with the original process (no isoagglutinin reduction), the model predicts lower hemolytic risk with anti-A donor screening and even lower hemolytic risk with IAC isoagglutinin reduction. CONCLUSION: IAC isoagglutinin reduction is predicted to reduce the HE risk with IVIG substantially. Physicians should be especially vigilant to HE risk in patients with blood group AB and, to a lesser extent, A when using IVIG products with high anti-A titers.