title: Concordance between Activated Partial Thromboplastin Time and Antifactor Xa Assay for Monitoring Unfractionated Heparin in Hospitalized Hyperbilirubinemic Patients.
abstract: BACKGROUND
  Activated partial thromboplastin time (aPTT) and antifactor Xa (anti-Xa) monitoring methods for unfractionated heparin (UFH) often disagree. The extent of discordance for those with elevated bilirubin remains unclear. Our objective was to evaluate concordance between activated aPTT and anti-Xa methods for hyperbilirubinemic patients on UFH.
  
  
  METHODS
  This was a retrospective cohort study of 26 patients hospitalized at Rhode Island Hospital between August 2014 and September 2014. Patients had at least one bilirubin measurement >5 mg/dL. After categorizing lab values, percent agreement and kappa were used to examine concordance between aPTT and anti-Xa.
  
  
  RESULTS
  Overall percent agreement between aPTT and anti-Xa was 50%. A nontherapeutic aPTT and therapeutic anti-Xa accounted for 98% of all disagreement. Specifically, 76.7% of disagreement was due to a subtherapeutic aPTT and a therapeutic anti-Xa. Unweighted kappa was 0.141 (95%CI: 0.048-0.235).
  
  
  CONCLUSIONS
  Concordance between aPTT and anti-Xa values was poor in hyperbilirubinemic patients.
authors.affiliation: Neurocritical Care Specialist, Department of Pharmacy, Rhode Island Hospital, Providence, RI.
authors.forename: Leana
authors.initials: L
authors.lastname: Mahmoud
authors.affiliation: Investigator, Department of Health Services, Policy, and Practice, Brown University School of Public Health, Providence, RI; Clinical Pharmacist Specialist, Department of Pharmacy, Rhode Island Hospital, Providence, RI.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Zullo
authors.affiliation: Medication Quality and Safety Specialist, Department of Pharmacy, Rhode Island Hospital, Providence, RI.
authors.forename: Donald
authors.initials: D
authors.lastname: McKaig
authors.affiliation: Director of Pharmacy, Rhode Island Hospital, The Miriam Hospital, and Bradley Hospital, Providence, RI.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Berard-Collins
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D001663:Bilirubin / Q000378:metabolism; D065427:Factor Xa Inhibitors / Q000378:metabolism / Q000627:therapeutic use*; D005260:Female; D006493:Heparin / Q000627:therapeutic use*; D006801:Humans; D006932:Hyperbilirubinemia / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D006493:Heparin; D001663:Bilirubin
keywords: Activated partial thromboplastin time; Rhode Island; antifactor Xa heparin assay; hyperbilirubinemia; unfractionated heparin