title: Lupus anticoagulant: performance of the tests as recommended by the latest ISTH guidelines.
abstract: OBJECTIVE
  Lupus anticoagulant (LA) is clinically the most relevant among all antiphospholipid antibody tests. Recently, new guidelines for LA detection were published. The objective of this retrospective cohort study was to compare tests recommended under these guidelines with other methods used for LA detection.
  
  
  METHODS
  The study group consisted of 336 subjects suffering from various autoimmune diseases. We used activated partial thromboplastin time (aPTT), diluted Russell viper venom time (dRVVT) and diluted prothrombin time (dPT) tests for LA detection together with a ratio between sensitive and insensitive aPTT reagent. We also tested if LA was dependent on β(2) glycoprotein I (β(2) GPI) using one of the recently described methods.
  
  
  RESULTS
  All LA tests performed were associated with a history of thrombosis. The highest odds ratio (OR) for thrombosis was found for β(2) GPI-dependent LA but sensitivity was low (OR = 8.4; specificity/sensitivity = 98%/15%). All LA tests showed a much stronger association with thrombosis than with pregnancy failure.
  
  
  CONCLUSIONS
  LA tested by aPTT and/or dRVVT (at least one out of two tests positive), as recommended by the guidelines, was associated less strongly with a history of thrombosis (OR = 4.1) than either of these tests separately (OR = 5.0 and 4.3, respectively). With both tests positive ('double LA positivity') the association with thrombosis was stronger (OR = 6.5) compared with only one positive test. In fact, 'double LA positivity', detected by combinations of any of the tests studied, was markedly associated with a history of thrombosis.
authors.affiliation: Department of Medicine, Jagiellonian University Medical College, Krakow, Poland. swadzba@diag.pl
authors.forename: J
authors.initials: J
authors.lastname: Swadzba
authors.forename: T
authors.initials: T
authors.lastname: Iwaniec
authors.forename: M
authors.initials: M
authors.lastname: Pulka
authors.forename: B
authors.initials: B
authors.lastname: De Laat
authors.forename: P G
authors.initials: PG
authors.lastname: De Groot
authors.forename: J
authors.initials: J
authors.lastname: Musial
mesh_terms: D000328:Adult; D000368:Aged; D017152:Antibodies, Antiphospholipid / Q000097:blood; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D001780:Blood Coagulation Tests / Q000379:methods* / Q000592:standards; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D017410:Practice Guidelines as Topic; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D011517:Prothrombin Time; D012189:Retrospective Studies; D013927:Thrombosis / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D020246:Venous Thrombosis / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D055815:Young Adult
chemical_list: D017152:Antibodies, Antiphospholipid; D016682:Lupus Coagulation Inhibitor