Haematologica 2004;89: supplement no. 8 - Supplements ...

174PostersPO-156DIAGNOSTIC EFFICACY OF LUPUS ANTICOAGULANT TESTAFTER THE ONSET OF ORAL ANTICOAGULANT TREATMENT:COMPARISION OF RESULTS FROM TWO LABORATORIESDel Bono R, Martini G, Volpi R, Testa S,*Morstabilini P,* Caimi LII Laboratorio Analisi (Centro FCSA n°28), AOSpedali Civili - Brescia Italy; *Istituto di PatologiaClinica, Centro di Emostasi e Trombosi, IstitutiOspedalieri di Cremona, ItalyBackground. Oral anticoagulant therapy (OAT) is atool to prevent thrombosis in patients affected byantiphospholipid syndrome (APS). Laboratory testingfor Lupus Anticoagulant (LA) is often problematicin anticoagulated patients because of their prolongedclotting times. Purpose. The aim of the studyis to evaluate the diagnostic efficacy of LA testingbefore and after the onset of OAT, comparing resultsfrom two different settings to improve accuracy.Patients. We enrolled 96 patients in OAT with (27)and without (69) APS. We tested 41 patients so far.All of them but one had been investigated for LAbefore the onset of OAT. Methods. Filtered plasmaswere tested for dilute Russell viper venom screen andconfirm test (IL dRVVT) at the II Laboratory, Brescia(BS) and with a four steps LA analysis at theHaemostasis and Thrombosis Centre, Cremona (CR):Stago PTT-LA sensitive, STA aPTT Kaolin, STA silicaaPTT, and the Cheshire modified dRVVT test (plateletderived reagent as the phospholipid trigger). Apooled plasma from pre-OAT LA negative anticoagulatedpatients was also prepared and run within theanalytical IL dRVVT session. Results. Results of testsrun in BS and in CR are shown in Table 1 and Table2, their comparision is shown in Table 3. Conclusions.We found a good agreement between LA testedbefore and after the onset of OAT and between thelaboratories. We had just three controversies: 1) Oneof the patients tested in BS showed a negative LAcompared to her previous result and to CR’s, likelydue to an excessive anticoagulation (INR=7.5). Infact, when the patient’s INR dropped to 2.0, her LAtested positive.Table 1.Pre-OATLA Test run i BS + − TOTTable 2.Pre-OATLA Test run in CR + − TOT+ 5 1 6Post-OAT − 1< 33 346 34 40K value= 0.80, p