title: Diagnostic accuracy of silica clotting time method for lupus anticoagulant in a clinical population with various symptoms of antiphospholipid syndrome.
abstract: BACKGROUND
  Correct interpretation of lupus anticoagulant (LA) tests is crucial for diagnosis of antiphospholipid syndrome (APS). This study assessed diagnostic accuracy of the SCT method in a clinical population with various symptoms of APS.
  
  
  METHODS
  Altogether 60 APS patients were consecutively recruited from a relevant clinical population. All cases had stable positivity of at least one of the reference tests (two other LA methods; anticardiolipin- and anti-β2-glycoprotein-I antibodies). Controls (n = 62) with negative reference tests were also consecutively recruited from the same clinical population.
  
  
  CONCLUSIONS
  Receiver operator characteristic (ROC) analysis for the SCT test to identify the APS cases showed area under the curve of 0.82 (95% CI 0.75-0.90). The positive cut-off defined by a non-parametric method (99 percentile in a healthy population) had specificity of 92%, but low sensitivity of 53%. The optimal cut-off corresponded to the 97.5 percentile (67% sensitivity and 92% specificity). Combined sensitivity of the positive diluted Russell Viper Venom time (dRVVT) and SCT tests was 73%, while specificity remained 92%. The sensitivity of the SCT method varied in different clinical subgroups and was highest in patients with rheumatic diseases and in patients with triple positivity of three reference methods.
authors.affiliation: Department of Laboratory medicine, University Hospital of North Norway, Tromsø, Norway Department of Medical Biology, UiT - the Arctic University of Norway, Tromsø, Norway Maria.Averina@unn.no.
authors.forename: M
authors.initials: M
authors.lastname: Averina
authors.affiliation: Department of Laboratory medicine, University Hospital of North Norway, Tromsø, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Johannesen
authors.affiliation: Department of Laboratory medicine, University Hospital of North Norway, Tromsø, Norway Department of Medical Biology, UiT - the Arctic University of Norway, Tromsø, Norway K.G. Jebsen - Thrombosis Research and Expertise Center (TREC), Department of Clinical Medicine, UiT - The Arctic University of Norway, Tromsø, Norway.
authors.forename: J
authors.initials: J
authors.lastname: Brox
mesh_terms: D000328:Adult; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood; D001777:Blood Coagulation; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time / Q000379:methods* / Q000592:standards; D011237:Predictive Value of Tests; D011517:Prothrombin Time; D012372:ROC Curve; D012016:Reference Values; D015203:Reproducibility of Results; D012822:Silicon Dioxide
chemical_list: D015415:Biomarkers; D016682:Lupus Coagulation Inhibitor; D012822:Silicon Dioxide
keywords: Antiphospholipid syndrome; lupus anticoagulant; thrombosis