Rapid and accurate Bayesian diagnosis of heparin-induced thrombocytopenia

摘要

Prompt diagnostic evaluation of suspected heparin-induced thrombocytopenia (HIT) is critical for guiding initial patient management. We assessed the performance of 3 immunoassays detecting anti-platelet factor 4 (PF4)/heparin antibodies, derived a diagnostic algorithm with a short analytical turnaround time (TAT), and prospectively validated the algorithm. Plasma samples were analyzed by Zymutest-HIA-IgG, HemosIL-AcuStar-HIT-IgG, and ID-H/PF4-PaGIA in retrospective (n = 221) and prospective (n = 305) derivation cohorts. We calculated likelihood ratios of result intervals and cutoff values with 100% negative (NPV) and positive (PPV) predictive values for a positive gold standard functional assay (heparin-induced platelet activation [HIPA]). A diagnostic algorithm was established based on the Bayesian combination of pretest probability and likelihood ratios of first- and second-line immunoassays. Cutoffs with 100% PPV for positive HIPA were >3.0 U/mL (HemosIL-AcuStar-HIT-IgG) and titer >= 16 (ID-H/PF4-PaGIA); cutoffs with 100% NPV were = 95% of cases within 60 minutes. This diagnostic approach improves initial management of patients with suspected HIT.