title: The presence of IgG antibodies against beta2-glycoprotein I predicts the risk of thrombosis in patients with the lupus anticoagulant.
abstract: BACKGROUND
  Lupus anticoagulant (LA) is a strong risk factor of thrombosis. However, a subgroup of patients positive for LA is unaffected by thrombosis and currently no predictive markers are available to identify patients positive for LA at increased risk for thrombosis.
  
  
  OBJECTIVE
  The aim of the study was to investigate whether anti-beta-2-glycoprotein I (anti-beta2GPI) or anticardiolipin antibodies (ACA) are associated with an increased risk of thrombosis in patients persistently positive for LA.
  
  
  METHODS
  A cohort of 87 consecutive patients persistently positive for LA was investigated, 55 with and 32 without a history of thrombosis. Immunoglobulin G (IgG) and M (IgM) antibodies against beta2GPI and cardiolipin were determined by enzyme-linked immunoassay.
  
  
  RESULTS
  Patients positive for LA with thrombosis had significantly higher levels of anti-beta2GPI IgG (median 16.7 standard units, interquartile range 3.0-75.2, P = 0.002) and of ACA IgG (41.1 IgG phospholipid units per mL, 8.9-109.0, P = 0.002) than those without thrombosis (2.6, 1.4-7.9 and 9.7, 4.6-22.1, respectively). Levels of anti-beta2GPI IgM and ACA IgM did not differ significantly between LA patients with and without thrombosis (P = 0.25 and 0.12, respectively). Elevated anti-beta2GPI IgG was associated with an increased risk for thrombosis (OR = 4.0, 95% CI 1.2-13.1), especially for venous thromboembolism (OR = 5.2, 95% CI 1.5-18.0).
  
  
  CONCLUSIONS
  Increased levels of anti-beta2GPI IgG were associated with thrombosis. We conclude that anti-beta2GPI IgG levels above normal predict an increased risk of thrombosis in patients persistently positive for LA.
authors.affiliation: Division of Haematology and Blood Coagulation, Department of Internal Medicine I, Medical University Vienna, Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Zoghlami-Rintelen
authors.forename: R
authors.initials: R
authors.lastname: Vormittag
authors.forename: T
authors.initials: T
authors.lastname: Sailer
authors.forename: S
authors.initials: S
authors.lastname: Lehr
authors.forename: P
authors.initials: P
authors.lastname: Quehenberger
authors.forename: H
authors.initials: H
authors.lastname: Rumpold
authors.forename: C
authors.initials: C
authors.lastname: Male
authors.forename: I
authors.initials: I
authors.lastname: Pabinger
mesh_terms: D000328:Adult; D017153:Antibodies, Anticardiolipin / Q000097:blood; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012306:Risk; D013927:Thrombosis / Q000209:etiology / Q000276:immunology*; D053482:beta 2-Glycoprotein I
chemical_list: D017153:Antibodies, Anticardiolipin; D001323:Autoantibodies; D006023:Glycoproteins; D007074:Immunoglobulin G; D016682:Lupus Coagulation Inhibitor; D053482:beta 2-Glycoprotein I