Seasonal variability is not observed in the rates of high anti-A and anti-B titers in plasma, apheresis platelet, and whole blood units tested by different methods

BACKGROUND: ABO-incompatible platelet transfusions are common, and transfusions with ABO-incompatible plasma are increasing with the use of group A plasma and group O whole blood (WB) in emergencies. Many centers screen blood products for anti-A and/or anti-B titers to help prevent hemolysis from ABO-incompatible transfusions, yet titer methods and definition of high titers are not standardized. STUDY DESIGN AND METHODS: This international multicenter study collected data on anti-A and anti-B titer practices for plasma, apheresis platelet (AP), and WB units from January 2015 through December 2017 to determine the prevalence of high-titer units using local definitions. RESULTS: A total of 87,701 plasma, AP and WB units were screened for high-titer anti-A and/or anti-B. High-titer detection rates for group A plasma ranged 0%–13.6%; group A AP 2.7%–9.3%; group O AP 2.3%–65.7%; and group O WB 6.4%–20.7%. At the one center that collected group B AP, the high-titer rate was 10.9%. High-titer rates varied from month to month, as well as between years for a given month. There was no clear pattern of when high-titer units were donated. CONCLUSION: The prevalence of high-titer plasma, AP, and WB units varies by titer method and local definition of high titer. Even at the lowest titer threshold of 50, a significant proportion of units had a high-titer antibody, although the clinical relevance of this finding needs further investigation.