Prevalence of Antiphospholipid Antibodies and Lupus Anticoagulant in Juvenile Patients with Objectively Documented Deep-vein Thrombosis

Abstract

The prevalence of lupus anticoagulant (LA) and antiphospholipid antibodies (APA) in young patients (<45 years) with deep-vein thrombosis (DVT) is not clearly defined yet. We studied 93 consecutive patients (36 males, 57 females; aged 15 to 45) with objectively documented DVT. A control group consisting of 100 nor mal, sex- and age-matched individuals was also investi gated. In all subjects, we evaluated prothrombin time (PT), partial thromboplastin time (PTT), AT III antigen and activity, protein C antigen and activity, free and total protein S antigen and protein S activity, fibrinogen, plas minogen, heparin cofactor II, plasminogen activator in hibitor (PAI), lupus anticoagulant (LA), and APA. For the assessment of LA, we used the PTT-LA kit (Boeh ringer Mannheim, Milan, Italy) as a screening test, with mixing studies with the Staclot-PNP kit and the Staclot- LA kit (Boehringer Mannheim, Milan, Italy) as confirma tory procedures. For the detection of APA, we used a commercially available enzyme-linked immunoassay (ELISA) (Asserachrom APA, Boehringer Mannheim, Mi lan, Italy). History was elicited in all patients to deter mine if the thrombotic episode was idiopathic or the re sult of a well-identified risk factor. LA was found in 11 (11.8%) patients. APA were positive in 13 (14%) and bor derline in 19 (20.4%) patients. In the control group, no patients were positive for LA or APA, but five exhibited borderline APA levels. LA was significantly more fre quent (p = 0.05) in patients with idiopathic DVT than in patients with secondary DVT; no difference was found for APA (p > 0.5). An inherited coagulation defect was found in seven (7.5%) patients. Our data suggest that the presence of LA or APA is associated with an increased incidence of thrombotic manifestation in young patients. Moreover LA is more frequent in patients with idiopathic DVT. Because the incidence of recurrent thrombotic manifestations in patients with LA or APA is estimated to be ∼50% within 2 years from the first thrombotic episode, the tests should be performed in all patients with juvenile thrombosis.