Open AccessUtility of grey zone testing strategy in transfusion transmissible infection testing in blood bank is of limited value!
Author(s) -
Gunjan Bhardwaj,
Aseem Kumar Tiwari,
Dinesh Arora,
Geet Aggarwal,
Swati Pabbi,
Divya Setya
Publication year - 2020
Publication title -
indian journal of pathology and microbiology/indian journal of pathology and microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.217
H-Index - 31
eISSN - 0974-5130
pISSN - 0377-4929
DOI - 10.4103/ijpm.ijpm_404_19
Subject(s) - hbsag , medicine , blood bank , blood transfusion , immunoassay , human immunodeficiency virus (hiv) , blood units , virology , immunology , emergency medicine , antibody , hepatitis b virus , virus
Several blood banks use grey zone (GZ) phenomenon (defined as samples with optical density within 10% below the cut off in enzyme immuno-assay [EIA]/chemiluminescence immunoassay [CLIA]) to further augment blood safety. There is paucity of data regarding usefulness of GZ sample and its application in Transfusion Transmissible Infection (TTI) screening procedures in blood transfusion services. We looked at our GZ sample results and their confirmatory test results to verify if it adds to blood safety in our set-up? We performed a prospective analytical study on blood donors' samples over two years. All the donors' samples were screened for TTI using CLIA. Samples with signal/cut-off ratio between ≥0.90 and <1.00 were classified under GZ. They were re-tested in duplicate and submitted to confirmatory testing: Neutralization Test for HBsAg, Immunoblot for HCV, and Western blot for HIV. Among the 50,064 blood donors donating the blood during study period, 573 (1.14%) donors were reactive for HBsAg, HCV, and HIV. Forty-seven (0.1%) TTI samples were GZ, but none was "confirmed positive." The utility of GZ testing seems to be limited. However, this may be continued for sake of "erring on the side of caution" and since this only results in negligible wastage (0.1%) of blood units.