Comparison of manual titrations to automated microplate and gel titration assays used in the screening of blood donors for production of Low-Titer O Whole Blood.

Background: The popularity of Low-Titer O Whole Blood (LTOWB) for treating trauma patients requires that donor centers and transfusion services make decisions on what titer testing capabilities to institute and an appropriate titer level threshold. This study compared the titer results determined by four methods to find a rate of agreement.

Study Design And Methods: Isohemagglutinin titers were tested on 300 plasma samples utilizing various methods, each determining IgM antibody levels by direct hemagglutination with A1 and B reference cells. The methods used were the Beckman Coulter's PK7300, Immucor's NEO Iris microplate technology, Ortho Clinical Diagnostics (OCD) Vision, and manual titrations.

Results: Only 42.7% of the samples tested showed agreement across all methods on ABO isohemaglutinin titer levels and only 32.5% demonstrated "High titer" agreement. Sample agreement was close to 90% if the Immucor method was excluded. At a <1:256 titer level threshold, the pass rate was 94.3% for Immucor, 89.7% for the PK7300, 87.3% for manual testing, and 75.7% for OCD's gel method. Sensitivity and specificity rates at a ± 1 titer level were respectively 100% and 95.4% for OCD's gel, 73.7% and 100% for Immucor, and 100% and 99.6% for the PK7300. Overall method accuracy was 91.7% for Immucor, 90.3% for the PK7300, and 86.7% for OCD's gel method as compared to manual titration.

Conclusion: All three automated methods perform comparably to the manual method at a ± 1 titer tolerance level. Based on these comparisons, a titer level of <1:256 would maximize LTOWB production regardless of the method used.