PREVALENCE OF ANTIPHOSPHOLIPID ANTIBODIES AND LUPUS ANTICOAGULANT IN JUVENILE PATIENTS WITH OBJECTIVELY DOCUMENTED DEEP-VEIN THROMBOSIS

The prevalence of lupus anticoagulant (LA) and antiphospholipid antibo dies (APA) in young patients (<45 years) with deep-vein thrombosis (DV T) is not clearly defined yet. We studied 93 consecutive patients (36 males, 57 females; aged 15 to 45) with objectively documented DVT. A c ontrol group consisting of 100 normal, sex- and age-matched individual s was also investigated. In all subjects, we evaluated prothrombin tim e (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, plasminogen, heparin cofactor II, pla sminogen activator inhibitor (PAI), lupus anticoagulant (LA), and APA. For the assessment of LA, we used the FIT-LA kit (Boehringer Mannheim , Milan, Italy) as a screening test, with mixing studies with the Stac lot-PNP kit and the Staclot-LA kit (Boehringer Mannheim, Milan, Italy) as confirmatory procedures. For the detection of APA, we used a comme rcially available enzyme-linked immunoassay (ELISA) (Asserachrom APA, Boehringer Mannheim, Milan, Italy). History was elicited in all patien ts to determine if the thrombotic episode was idiopathic or the result of a well-identified risk factor. LA was found in 11 (11.8%) patients . APA were positive in 13 (14%) and borderline in 19 (20.4%) patients. In the control group, no patients were positive for LA or APA, but fi ve exhibited borderline APA levels. LA was significantly more frequent (p = 0.05) in patients with idiopathic DVT than in patients with seco ndary DVT; no difference was found for APA (p > 0.5). An inherited coa gulation defect was found in seven (7.5%) patients. Our data suggest t hat the presence of LA or APA is associated with an increased incidenc e of thrombotic manifestation in young patients. Moreover LA is more f requent in patients with idiopathic DVT. Because the incidence of recu rrent thrombotic manifestations in patients with LA or APA is estimate d to be similar to 50% within 2 years from the first thrombotic episod e, the tests should be performed in all patients with juvenile thrombo sis.