Persistent Antiphospholipid Antibody (APL) in Asymptomatic Carriers as a Risk Factor for Future Thrombotic Events: A Nationwide Prospective Study

Abstract

Objectives 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. Design We conducted a prospective nationwide cohort study. Setting 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. Participants Participants included adult asymptomatic aPL carriers recognized in Finland during 1971-2009. Main outcome measure 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…