title: Evaluation of appropriate serologic testing for suspected heparin-induced thrombocytopenia.
abstract: OBJECTIVE
  The predictive value of clinical "4-T's" scoring in patient selection for serologic testing to confirm suspected heparin-induced thrombocytopenia (HIT) was evaluated.
  
  
  METHODS
  In a chart review-based study at a large hospital, all adult inpatients who underwent enzyme-linked immunosorbent assay (ELISA) testing for HIT-antibody detection during a two-year period were identified. Scoring of the 4 T's (degree of thrombocytopenia, timing of symptom onset, presence of thrombosis or other sequelae, and other potential causes) was retrospectively performed on a random sample of cases (n = 70) by three pharmacist investigators. Based on the 4-T's scores, the probability of HIT confirmation via ELISA testing was classified as low, intermediate, or high; by comparing those classifications with documented ELISA results, the positive predictive value of 4-T's scoring was calculated. Interrater variability in 4-T's scoring was also assessed.
  
  
  RESULTS
  4-T's scoring of the 70 randomly selected cases indicated low, intermediate, and high probabilities of HIT confirmation via ELISA testing in 52, 17, and 1 case, respectively. Negative ELISA results were documented in the records of 37 patients in the low-probability group; the 4-T's scoring system was calculated to have an adjusted negative predictive value of 77.3%. The calculation of Gwet's agreement coefficient indicated substantial agreement in 4-T's scoring by the three raters.
  
  
  CONCLUSIONS
  The study results suggest that among patients whose 4-T's scores indicate a low probability of HIT, the results of subsequent ELISA testing for HIT antibodies are likely to be negative in about 8 of 10 cases.
authors.affiliation: Shands Jacksonville Medical Center, 655 West 8th Street, Jacksonville, FL 32209, USA. donald.floresca@jax.ufl.edu
authors.forename: Donald
authors.initials: D
authors.lastname: Floresca
authors.forename: Lori
authors.initials: L
authors.lastname: Dupree
authors.forename: Sharon
authors.initials: S
authors.lastname: Basile
authors.forename: Paul
authors.initials: P
authors.lastname: Tan
mesh_terms: D000328:Adult; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012698:Serologic Tests / Q000379:methods; D013921:Thrombocytopenia / Q000139:chemically induced / Q000175:diagnosis*; D013997:Time Factors
chemical_list: D006493:Heparin