Direct Antiglobulin Test Positivity in Blood Donors and Impact on Donor Health and Transfusion Services: A Seven-Year Retrospective Study from Eastern India.

The aim of this study is to determine the incidence of a positive direct antiglobulin test (DAT) in a population of blood donors in Eastern India and to explore the impact of DAT positivity on donor health and transfusion services. We conducted a retrospective study on 89,402 blood donors over a seven-year period (2018-2024). Positive DAT results were detected using the column agglutination technique (CAT) following a difficulty in the cross-match, a positive weak D test on donor RhD typing, and a positive autocontrol encountered during donor antibody screening. Furthermore, DAT was subclassified, and donors exhibiting a DAT strength of ≥ 2 + were recalled and investigated. We found the DAT was positive in 54 donors (0.06%) with an overall incidence of 1:1,656. The DAT-positive donors presented predominantly as crossmatch incompatibility (85.2%). The majority of blood donors (96.3%) were IgG positive. Of the 39 donors who were evaluated, two were found to have autoimmune diseases. The remaining donors showed no signs of hemolysis and were in good health. The incidence of positive DAT results in eastern Indian blood donors is higher, leading to increasing non-utilization of collected blood units. There is a need for a national policy for managing DAT-positive donors in India.