title: Evaluation of two new automated chemiluminescent assays (HemosIL® AcuStar HIT-IgG and HemosIL® AcuStar HIT-Ab) for the detection of heparin-induced antibodies in the diagnosis of heparin-induced thrombocytopenia.
abstract: BACKGROUND
  Recently, two new, fully automated quantitative chemiluminescent immunoassays, the HemosIL(®) AcuStar HIT-IgG (PF4-H), specific for IgG anti-PF4/H antibodies, and the HemosIL(®) AcuStar HIT-Ab(PF4-H), detecting IgG, IgM and IgA anti-PF4/H antibodies, were introduced into the market. In this study, their performance was compared mutually and with the Zymutest HIA IgG and HIA IgGAM ELISA.
  
  
  METHODS
  Citrated plasmas from 87 patients with clinical suspicion of heparin-induced thrombocytopenia (HIT) were analyzed with all four assays and with a functional confirmation assay. Apart from the manufacturer's cutoffs, optimalized cutoffs were evaluated as well.
  
  
  RESULTS
  Sensitivities of all assays were 100%. The Acustar HIT-IgG assay showed a higher specificity compared with the HIT-Ab assay (85%vs. 73%), using the manufacturer's cutoffs. Specificities of all assays, except for the AcuStar HIT-IgG, could be significantly improved when altering the cutoff. Titers were significantly higher for the HIT-Ab assay compared with the HIT-IgG assay (P = 0.0001). This was also the case for the patients with confirmed HIT (P = 0.0495), indicating that the one cutoff (1.0 OD) for both Acustar assays, as proposed by the manufacturer, can be adapted for the AcuStar Hit-Ab assay resulting in an increased specificity.
  
  
  CONCLUSIONS
  Performance characteristics of the Acustar HIT-IgG and HIT-Ab assay are comparable to the Zymutest HIA IgG and HIA IgGAM.
authors.affiliation: Coagulation Laboratory, Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, Ghent, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Van Hoecke
authors.forename: K
authors.initials: K
authors.lastname: Devreese
mesh_terms: D000906:Antibodies / Q000032:analysis*; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis; D001331:Automation; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods* / Q000592:standards*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis*
chemical_list: D000906:Antibodies; D000888:Antibodies, Anti-Idiotypic; C048844:anti-IgG; D006493:Heparin