LAUSR

The aims of the study were to perform an instrument validation of the HemosIL HIT-Ab (PF4-H) Assay and to compare the sensitivities and specificities of the three HIT tests (HemosIL HIT-Ab [PF4-H] Assay, PIFA Heparin/PF4 Assay, and Immucor PF4 ELISA) versus the gold standard Serotonin Release Assay performed in ARUP Laboratories and versus each other. The HemosIL HIT-Ab (PF4-H) Assay was validated on the ACL TOP 750 using calibrators, controls, and samples from UF Pathology Laboratories and ARUP Laboratories that were previously tested for the HIT-Ab IgG via an ELISA method. EP Evaluator was used to calculate statistical data. A total of 116 samples were assayed using the HemosIL HIT-Ab (PF4-H) Assay and the PIFA Heparin/PF4 Rapid Assay. Overall, there were 125 positive tests and 255 negative tests for anti-PF4-H (ACL 39 positive, 77 negative; 11 positive, 105 negative; 60 positive, 56 negative). There were 15 positive and 17 negative for the SRA. The comparison between the ACL TOP and SRA had a sensitivity of 80.0% and specificity of 35.3%. ELISA vs SRA had a sensitivity of 100.0% but had a 0.0% specificity. The PIFA vs SRA correlation had a sensitivity of 0.0% and specificity of 88.2%. The ACL TOP versus UF Health’s current HIT ELISA method had a good comparison as well, with a sensitivity of 61.7% and a specificity of 96.4%. The three HIT methods (ACL TOP, ELISA, and PIFA) compared to the SRA showed that the ACL TOP had a good positive agreement, but poor negative agreement; however, the ACL TOP had a very good negative agreement with the ELISA method. The PIFA cartridge test had an overall poor performance with no positive agreement with the SRA and poor sensitivity versus the ACL TOP and ELISA methods.