Anti-A/B isoagglutinin reduction in an intravenous immunoglobulin product and risk of hemolytic anemia: a hospital-based cohort study.

BACKGROUND Intravenous immunoglobulins (IVIG) are derived from large human plasma pools. IVIG-associated hemolytic anemia (HA) is a known class effect, likely attributed to dose-dependent passive transfer of anti-A/B isoagglutinins. Two isoagglutinin reduction steps were implemented in the manufacturing process of Privigen (human 10% liquid IVIG): exclusion of high-anti-A-titer donors in 2013, replaced by specific immunoaffinity chromatography in 2015. We aim to estimate the clinical effectiveness of both measures. STUDY DESIGN AND METHODS Using the US hospital-based Premier Healthcare Database, three Privigen cohorts were generated based on calendar periods indicative of manufacturing changes: Period 1 (baseline) January 2008 to December 2012, Period 2 (high-anti-A-titer donor exclusion) October 2013 to December 2015, and Period 3 (immunoaffinity chromatography) October 2016 to April 2019. HA within a 10-day at-risk period after Privigen administrations was identified from review of patient record summaries. Incidence rate ratios (IRRs) were estimated from Poisson regression (Period 1 reference) adjusting for hospital setting, sex, age, Privigen indication, dose, and first use. RESULTS Crude incidence rates of HA were 1.49 per 10,000 person-days in Period 1 (38 HA, 9439 patients), 1.01 in Period 2 (20 HA, 7710 patients), and 0.14 in Period 3 (3 HA, 7759 patients). Adjusted IRR for HA in Period 2 was 0.71 (95% confidence interval [CI], 0.41-1.23), and in Period 3 was 0.10 (0.03-0.33) compared with Period 1. The IRR for HA in Period 3 compared with Period 2 was 0.14 (95% CI, 0.04-0.47). CONCLUSION Implementation of immunoaffinity chromatography in Privigen manufacturing resulted in a significant 90% reduction of HA risk. HA has become a rare event in association with Privigen use.