Diagnosis of Heparin-Induced Thrombocytopenia: Development and Validation of a Predictive Clinical Score Based on Objective Features Identified by a Multivariate Analysis of a Multinational Prospective Study

Background: Diagnosis of heparin-induced thrombocytopenia (HIT) is based on a composite of clinical likelihood and laboratory testing. We aimed to develop a diagnostic score derived from multivariate analysis of clinical features, including platelet count changes, prospectively recorded in patients with suspected HIT. Methods: This multinational observational study (ClinicalTrials.gov no. NCT00748839) included 2280 adult patients with suspected HIT: 1597 (derivation cohort) formed the basis for developing the scoring system, subsequently validated in 683 additional randomly selected patients (validation cohort). HIT was diagnosed by two independent adjudicators based on clinical features, l…