Objective: To evaluate the clinical manifestations, type and persistence of antiphospholipid (aPL) antibodies, and outcomes of patients evaluated in a hematology practice clinic for the diagnosis of antiphospholipid syndrome (APLS).

Methods: We systematically reviewed the medical records of all patients referred to our Hemostasis and Thrombosis Practice Clinic for evaluation of APLS from January 1995 to July 2005. APLS was defined by the Sapporo criteria.

180 patients were identified who either had APLS as defined by the Sapporo criteria or had documented aPL antibodies on 2 separate occasions at least 6 weeks apart without any clinical manifestation for APLS. Data collected included demographics, clinical manifestations, type of aPL antibodies, presence or absence of lupus anticoagulant (LAC), persistence or fluctuation of the aPL antibodies, presence of other thrombophilias, antithrombotic therapy, and outcomes.

Results: Of the 180 patients, 141 were females and 39 were males. The age range was 21 to 89 yr. 119 patients (66%) fulfilled the clinical criteria for APLS and 61(34%) did not. Among the 119 patients with APLS, the clinical manifestations included arterial thromboembolism (ATE) in 53 (46 idiopathic, 7 secondary), venous thromboembolism (VTE) in 44 (31 idiopathic, 13 secondary), both ATE and VTE in 7 and pregnancy losses (PL) in 30. Among the 30 patients with PL, 19 had recurrent PL before the 10th week of gestation and 11 had PL after the 10th week of gestation. 5 patients with PL also had ATE and/or VTE.

94 patients had anticardiolipin (aCL) antibody (medium titer IgG isotype), 57 had aCL antibody (high titer IgG), 29 had antiphosphatidylserine (aPS) antibody (medium titer IgG), 27 had aPS antibody (high titer IgG), 11 had anti-β2 glycoprotein I (anti-β2GPI) antibody (medium titer), 13 had anti-β2GPI antibody (high titer), 47 had aCL antibody (medium titer IgM), 15 had aCL antibody (high titer IgM), 74 had aPS antibody (medium titer IgM), 43 had aPS antibody (high titer IgM), 20 had anti-β2GPI medium titer IgM, 12 had anti-β2GPI high titer IgM, 10 had anti-β2GPI medium titer IgA isotype, 6 had anti-β2GPI high titer IgA isotype and 36 had LAC. 115 patients had persistent aPLA and 65 had fluctuating aPLA.

33 patients had other thrombophilias: factor V Leiden (n=5), prothrombin gene mutation (G20210A) (n=6), protein S deficiency (n=4), increased homocysteine level (>12 mcmol/L) (n=9), hyperfibrinogenemia (n=3), elevated factor VIII (n=4) and factor XI (n=1) and plasminogen deficiency (n=1).

Antithrombotic therapy included warfarin in 71 patients, aspirin in 85, clopidogrel in 3, and LMWH in 36 (2 on chronic therapy and 34 during pregnancy). 21 patients were on no antithrombotic medications.

Of the 180 patients, 110 patients had succesful outcomes defined as either absence of recurrent thrombosis or pregnancy losses. 7 patients had recurrent PL while 10 had recurrent thrombosis. 1 patient died. 52 patients were lost to follow-up.

Conclusions: The majority of our patients with APLS were women. The most common clinical manifestations were ATE, followed by VTE and PL. The most prevalent aPL antibody was aCL medium titer IgG isotype and the least common was anti-β2GPI high titer IgA. Antithrombotic therapy resulted in successful outcomes in approximately 2/3 of patients.

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