title: The HIT Expert Probability (HEP) Score: a novel pre-test probability model for heparin-induced thrombocytopenia based on broad expert opinion.
abstract: BACKGROUND
  The diagnosis of heparin-induced thrombocytopenia (HIT) is challenging. Over-diagnosis and over-treatment are common.
  
  
  OBJECTIVE
  To develop a pre-test clinical scoring model for HIT based on broad expert opinion that may be useful in guiding clinical decisions regarding therapy.
  
  
  METHODS
  A pre-test model, the HIT Expert Probability (HEP) Score, was constructed based on the opinions of 26 HIT experts. Fifty patients referred to a reference laboratory for HIT testing comprised the validation cohort. Two hematology trainees scored each patient using the HEP Score and a previously published clinical scoring system (4 T's). A panel of three independent experts adjudicated the 50 patients and rendered a diagnosis of HIT likely or unlikely. All subjects underwent HIT laboratory testing with a polyspecific HIT ELISA and serotonin release assay (SRA).
  
  
  RESULTS
  The HEP Score exhibited significantly greater interobserver agreement [intraclass correlation coefficient: 0.88 (95% CI 0.80-0.93) vs. 0.71 (0.54-0.83)], correlation with the results of HIT laboratory testing and concordance with the diagnosis of the expert panel (area under receiver-operating curve: 0.91 vs. 0.74, P = 0.017) than the 4 T's. The model was 100% sensitive and 60% specific for determining the presence of HIT as defined by the expert panel and would have allowed for a 41% reduction in the number of patients receiving a direct thrombin inhibitor (DTI).
  
  
  CONCLUSIONS
  The HEP Score is the first pre-test clinical scoring model for HIT based on broad expert opinion, exhibited favorable operating characteristics and may permit clinicians to confidently reduce use of alternative anticoagulants. Prospective multicenter validation is warranted.
authors.affiliation: University of Pennsylvania, Philadelphia, PA Duke University, Durham, NC, USA. adam.cuker@uphs.upenn.edu
authors.forename: A
authors.initials: A
authors.lastname: Cuker
authors.forename: G
authors.initials: G
authors.lastname: Arepally
authors.forename: M A
authors.initials: MA
authors.lastname: Crowther
authors.forename: L
authors.initials: L
authors.lastname: Rice
authors.forename: F
authors.initials: F
authors.lastname: Datko
authors.forename: K
authors.initials: K
authors.lastname: Hook
authors.forename: K J
authors.initials: KJ
authors.lastname: Propert
authors.forename: D J
authors.initials: DJ
authors.lastname: Kuter
authors.forename: T L
authors.initials: TL
authors.lastname: Ortel
authors.forename: B A
authors.initials: BA
authors.lastname: Konkle
authors.forename: D B
authors.initials: DB
authors.lastname: Cines
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects*; D005260:Female; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D015588:Observer Variation; D011336:Probability; D012372:ROC Curve; D011795:Surveys and Questionnaires; D013921:Thrombocytopenia / Q000139:chemically induced*
chemical_list: D000925:Anticoagulants; D006493:Heparin