title: Persistent antiphospholipid antibody (aPL) in asymptomatic carriers as a risk factor for future thrombotic events: a nationwide prospective study.
abstract: OBJECTIVE
  The long-term prognosis of individuals fulfilling the laboratory criteria, but not clinical criteria, of antiphospholipid syndrome (APS) has not been widely investigated. The primary aim of this study was to evaluate the incidence of first thrombotic event (deep venous thrombosis (DVT), pulmonary embolism (PE), myocardial infarction (MI), stroke or transient ischaemic attack (TIA) in a nationwide antiphospholipid antibody (aPL) carrier cohort.
  
  
  METHODS
  We conducted a prospective nationwide cohort study.
  
  
  METHODS
  The aPL profile of participants was recorded from the laboratory database. Information was collected about thrombotic and pregnancy complications, subsequent medical history, other risk factors for thrombosis, use of prophylactic antithrombotic medication and general health.
  
  
  METHODS
  Participants included adult asymptomatic aPL carriers recognized in Finland during 1971-2009.
  
  
  METHODS
  The main outcome measure was incidence of first thrombotic event.
  
  
  RESULTS
  A total of 119 (89% female) aPL carriers were followed for mean (SD) of 9.1 (7.5) years (range 3-41 years). Sixty-one per cent of the study participants had autoimmune disease, most often systemic lupus erythematosus (SLE). Thirty-six of 119 (30%) were either double or triple positive, 56% single lupus anticoagulant (LA) positive, and 8% and 5% single anticardiolipin antibodies (aCL) and anti-β2glycoprotein I antibodies (aβ2GPI) positive, respectively. Nine (7.6%) study patients experienced a first thrombotic event (five DVT, one PE, two MI, one TIA) mean (SD) 7.2 (8.3) years (range 1-26 years) after aPL detection (annual incidence rate 0.8%). All individuals who developed thrombotic complications had autoimmune disease. Annual rate of first thrombotic event in carriers of single positivity (0.65%) was equal to the known risk of thrombosis in the healthy Caucasian population, whereas the rate was two times higher in carriers of double or triple positivity (1.27%). Sixteen of 79 (20%) women experienced pregnancy complications.
  
  
  CONCLUSIONS
  Double or triple positivity for aPL is a risk factor for future thrombotic events, especially in individuals with an underlying autoimmune disease, whereas single positivity does not seem to carry an elevated risk of thrombosis.
authors.affiliation: Department of Internal Medicine, Keski-Suomi Central Hospital, Jyväskylä, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Mustonen
authors.affiliation: Department of Haemostasis, Finnish Red Cross Blood Transfusion Service, Helsinki, Finland University of Helsinki, Faculty of Medicine, Helsinki, Finland.
authors.forename: K V
authors.initials: KV
authors.lastname: Lehtonen
authors.affiliation: Department of Haemostasis, Finnish Red Cross Blood Transfusion Service, Helsinki, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Javela
authors.affiliation: Department of Haemostasis, Finnish Red Cross Blood Transfusion Service, Helsinki, Finland marja.puurunen@veripalvelu.fi.
authors.forename: M
authors.initials: M
authors.lastname: Puurunen
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology / Q000276:immunology; D000293:Adolescent; D000328:Adult; D000368:Aged; D017153:Antibodies, Anticardiolipin / Q000097:blood; D017152:Antibodies, Antiphospholipid / Q000097:blood*; D058070:Asymptomatic Diseases; D001327:Autoimmune Diseases / Q000097:blood / Q000150:complications / Q000453:epidemiology*; D002648:Child; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D002546:Ischemic Attack, Transient / Q000453:epidemiology* / Q000276:immunology; D016682:Lupus Coagulation Inhibitor / Q000097:blood; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000276:immunology; D011247:Pregnancy; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000453:epidemiology* / Q000276:immunology; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000276:immunology; D013997:Time Factors; D020246:Venous Thrombosis / Q000453:epidemiology* / Q000276:immunology; D055815:Young Adult; D053482:beta 2-Glycoprotein I / Q000276:immunology
chemical_list: D017153:Antibodies, Anticardiolipin; D017152:Antibodies, Antiphospholipid; D005343:Fibrinolytic Agents; D016682:Lupus Coagulation Inhibitor; D053482:beta 2-Glycoprotein I
keywords: Antiphospholipid antibodies; anticardiolipin antibodies; lupus anticoagulant; thrombosis; β2-glycoprotein I antibodies