title: Rivaroxaban Therapy, False-Positive Lupus Anticoagulant Screening Results, and Confirmatory Assay Results.
abstract: OBJECTIVE
  To examine the effects of patients taking the direct blood coagulation factor Xa inhibitor rivaroxaban on lupus anticoagulant testing results in a clinical setting.
  
  
  METHODS
  We reviewed the results of lupus anticoagulant testing performed over a 2-year period. Of 59 patients who met criteria for a lupus anticoagulant, 18 were taking rivaroxaban. We reviewed and compared the parameters of lupus anticoagulant testing.
  
  
  RESULTS
  The average dilute Russell viper venom time (DRVVT) and normal plasma-mix screening results to confirmation ratios in rivaroxaban-naïve patients were 1.6 and 1.7, respectively. In the rivaroxaban group, the same parameters were 1.7 and 1.6, respectively (P = - 0.28 and 0.46, respectively). For 15 of 18 patients taking rivaroxaban, results were corrected on the confirmation steps of both tests.
  
  
  CONCLUSIONS
  Rivaroxaban confounds lupus anticoagulant testing because the DRVVT is prolonged in these patients but it also corrects with excess phospholipid, mimicking a lupus anticoagulant. Patient medication review is critical to avoid false-positive findings and inappropriate diagnosis of antiphospholipid syndrome.
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE.
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Murer
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE scott.koepsell@unmc.edu.
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Pirruccello
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Koepsell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D065427:Factor Xa Inhibitors / Q000627:therapeutic use*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000097:blood*; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis*; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D010743:Phospholipids / Q000032:analysis; D000069552:Rivaroxaban / Q000627:therapeutic use*
chemical_list: D065427:Factor Xa Inhibitors; D007155:Immunologic Factors; D016682:Lupus Coagulation Inhibitor; D010743:Phospholipids; D000069552:Rivaroxaban
keywords: antiphospholipid syndrome; lupus anticoagulant; rivaroxaban