title: A Practical Guide to Ordering and Interpreting Coagulation Tests for Patients on Direct Oral Anticoagulants in Singapore.
abstract: BACKGROUND
  Direct oral anticoagulants (DOACs) are establishing themselves as principle choices for the treatment of a variety of thrombotic disorders. DOACs are also known to affect common coagulation tests which are routinely performed for patients in clinical practice. An understanding of their varied effects is crucial for the appropriate ordering of coagulation tests and their interpretation.
  
  
  METHODS
  Laboratories in public and private healthcare institutions and commercial sectors were surveyed on coagulation tests offered and their methods. A Medline and bibliography search, including a search on search engines, was performed for publications reporting the effects of dabigatran, apixaban and rivaroxaban on these coagulation tests. These papers were reviewed and summarised for consensus recommendations.
  
  
  RESULTS
  Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are variably affected by the DOACs and dependent of the coagulation assays used. Clinicians must know which laboratory has performed these tests to logically interpret test results. A normal PT or aPTT does not exclude the presence of residual DOACs effect. The thrombin time is sensitive to dabigatran but not apixaban or rivaroxaban. Specialised coagulation tests such as thrombophilia tests are also variably affected by the DOACs. All laboratories in Singapore however, employ similar test methods permitting a common set of recommendations for specialised coagulation testing.
  
  
  CONCLUSIONS
  Knowledge of the effects of DOACs on coagulation testing is essential to determine the appropriateness of performing such tests and interpreting them coherently. Practical recommendations which are tests and location-specific are set out in this paper.
authors.affiliation: Department of Haematology, Singapore General Hospital, Singapore.
authors.forename: Wan Hui
authors.initials: WH
authors.lastname: Wong
authors.forename: Christina Yc
authors.initials: CY
authors.lastname: Yip
authors.forename: Christina Ll
authors.initials: CL
authors.lastname: Sum
authors.forename: Chuen Wen
authors.initials: CW
authors.lastname: Tan
authors.forename: Lai Heng
authors.initials: LH
authors.lastname: Lee
authors.forename: Eng Soo
authors.initials: ES
authors.lastname: Yap
authors.forename: Ponnudurai
authors.initials: P
authors.lastname: Kuperan
authors.forename: Wen Chang
authors.initials: WC
authors.lastname: Ting
authors.forename: Heng Joo
authors.initials: HJ
authors.lastname: Ng
mesh_terms: D000991:Antithrombins / Q000627:therapeutic use; D001780:Blood Coagulation Tests; D000069604:Dabigatran / Q000627:therapeutic use*; D065427:Factor Xa Inhibitors / Q000627:therapeutic use*; D006801:Humans; D010314:Partial Thromboplastin Time; D017410:Practice Guidelines as Topic; D011517:Prothrombin Time; D011720:Pyrazoles / Q000627:therapeutic use*; D011728:Pyridones / Q000627:therapeutic use*; D000069552:Rivaroxaban / Q000627:therapeutic use*; D012846:Singapore
chemical_list: D000991:Antithrombins; D065427:Factor Xa Inhibitors; D011720:Pyrazoles; D011728:Pyridones; C522181:apixaban; D000069552:Rivaroxaban; D000069604:Dabigatran