Abstract
According to the literature, hemolysis due to ABO incompatible (ABOi) plasma is reported to occur with an incidence of approximately 50 in 10 lakhs transfusions. Most of the critical titers reported were based on assessments of titers following hemolysis due to ABOi plasma/platelet transfusion. This is one of the first studies from India to establish a critical threshold for ABO titers based on hemolysin test results. A prospective observational study was conducted with an estimated sample size of 340, including O blood group regular voluntary donors of the district who provided consent for participation in the study. Hemolysin test and antibody titers were performed using the conventional tube technique. The critical titer was determined based on the hemolysin test using the receiver operating characteristic curve (ROC). Statistical analysis was performed using the MedCalc Statistical Software version 14.8.1. Out of the 6744 donors, a total of 350 (37.8%) having blood group 'O' were recruited through purposive sampling, of which 321 were males (91.7%) and 29 were females (8.2%) with a mean age of 28 (± 7.7) years. A critical titer above 128 for both IgG anti-A and anti-B may be considered based on the predictability of the respective hemolysin test results. IgG and AHG phase titers below 128 were associated with negative hemolysin tests for both anti-A and anti-B antibodies. A threshold of ≥ 128 for IgG anti-A and anti-B should be considered as critical titers, below which it is safe for ABOi plasma transfusion.