Incidence of a first thromboembolic event in asymptomatic carriers of high risk antiphospholipid antibody profile: a multicenter prospective study

Vittorio Pengo, Amelia Ruffatti, Cristina Legnani, Sophie Testa, Tiziana Fierro, Francesco Marongiu, Valeria De Micheli, Paolo Gresele, Marta Tonello, Angelo Ghirarduzzi, Elisa Bison, Gentian Denas, Alessandra Banzato, Seena Padayattil Jose and Sabino Iliceto


Persistent antiphospholipid (aPL) antibodies are occasionally found in subjects without prior history of thromboembolic (TE) events raising the dilemma of whether to initiate or not a primary thromboprophylaxis. A first TE event is considered rare in aPL carriers but previous studies did neither consider the aPL profile nor the test positivity was confirmed in a reference laboratory. In this study 104 subjects with high-risk aPL-profile [positive Lupus Anticoagulant (LA), anticardiolipin (aCL) and anti β2Glycoprotein I (aβ2GPI) antibodies, triple positivity)] confirmed in a reference laboratory, were followed up for a mean of 4.5 tears. There were 25 first thromboembolic events (5.3% per year): the cumulative incidence after 10 years was 37.1% (95% CI, 19.9-54,3). On multivariate analysis male sex [HR= 4.4 (95% CI 1.5-13.1), p=0.007] and risk factors for venous thromboembolism [HR=3.3 (95% CI 1.3-8.5), p=0.01] were independent predictors for TE events. Aspirin did not significantly affect the incidence of TE. In conclusion the occurrence of a first TE in carriers of high-risk aPL-profile is considerable; it is more frequent among male subjects and in the presence of additional risk factors for venous TE. These data can help in the decision to initiate primary thromboprophylaxis in these subjects.

  • Submitted March 1, 2011.
  • Accepted June 30, 2011.