Evaluation of an IgG anti-PF4/H chemiluminescent immunoassay in the diagnosis of heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a life-threatening complication of heparin therapy, mediated by immunoglobulin G (IgG) antibodies targeting platelet factor 4/heparin (PF4/H) complexes. Prompt and accurate diagnosis is critical to ensure appropriate treatment and improve outcomes. We aimed to evaluate the performance of the rapid chemiluminescent immunoassay (CLIA) HemosIL AcuStar HIT-IgG (Werfen) for detecting IgG anti-PF4/H antibodies for HIT diagnosis compared with the Zymutest HIA IgG (Hyphen BioMed) enzyme-linked immunosorbent assay (ELISA). This single-center retrospective cohort included all patients with suspected HIT (4Ts score >3). CLIA and ELISA were performed and compared, and results were evaluated against the serotonin-release assay. We included 113 patients with suspected HIT, and HIT was confirmed in 43 (38.1%). Discordant results occurred in 5 patients (4.4%) with confirmed HIT: 3 patients had positive ELISA and negative CLIA, one had both negative ELISA and CLIA, and one had negative ELISA and positive CLIA. CLIA demonstrated a high diagnostic accuracy, with a sensitivity of 90.7% (95% confidence interval [CI], 82.0-99.4) and specificity of 80.0% (95% CI, 70.6-89.3). ELISA showed a sensitivity of 95.3% (95% CI, 89.1-100.0) and negative predictive value of 96.3% (95% CI, 91.3-100.0) compared with 93.3% (95% CI, 87.0-99.6) for CLIA. No significant difference was observed between the 2 tests for sensitivity or specificity. Positive and negative percent agreements were 86.4% (95% CI, 77.7-95.2) and 96.3% (95% CI, 91.3-101.3), respectively. Overall percent agreement was 91.2% (95% CI, 85.9-96.4). This study supports the utility of CLIA as a rapid diagnostic tool for HIT optimizing clinical decision-making and patient management.